CAIRO, Egypt — Turkey’s president said Saturday that his country would do “whatever is necessary” in response to the downing of a Turkish military jet by Syria, adding a new complication to the tense relationship between the former allies split by Turkey’s support for Syrian rebels trying to overthrow the government.

“It is not possible to cover over a thing like this,” said President Abdullah Gul of Turkey, according to the Anatolia news agency. “Whatever is necessary will no doubt be done.”

Syria said Friday that its military forces had shot down a Turkish F-4 jet that had entered its airspace just off the Syrian coast. But Gul said Saturday that while the exact route of the plane had not yet been confirmed, it was routine for military jets flying at high speeds to briefly cross into another country’s airspace, and thatthe jet’s presence over Syrian territory was not intended as a hostile act.

The plane went down over the Mediterranean eight miles off the coast of the Syrian province of Latakia and south of the Turkish province of Hatay. On Saturday, Turkish officials confirmed that parts of the jet had been recovered. Syria claimed the jet was 0.62 of a mile inside its border. It said Syrian forces realized it was a Turkish jet only after firing at it.

A Turkish official said Turkey was examining the plane’s radar route and other flight data to find out whether the aircraft was flying over Syrian territory when it was shot down. The official spoke on condition of anonymity because he was not authorized to brief journalists and would provide no further details.

Turkey has not described the plane’s specific mission.

Gul said the two governments were communicating at a high level despite the absence of a Turkish ambassador in Syria since Turkey closed its embassy in March. Syria’s state news agency, SANA, reported that the Syr-ian and Turkish navies had established contact and were searching for the missing pilots.

“We have no hostile intentions against Turkey,” Jihad Makdissi, a spokesman for the Syrian Foreign Ministry, told the Lebanese broadcaster LBC.

Faruk Celik, Turkey’s labor and social security minister, said that even if Syria’s airspace had been violated, the Syrian response was unacceptable.

“Turkey cannot endure it in silence,” Celik said.

Gul did not specify whether he meant to respond with diplomatic or military measures. But Turkey said after an April border shooting - in which two people in a Turkish refugee camp died - that itwould call on its NATO allies to intervene if it felt its security was being threatened.

Other Turkish officials urged restraint. Deputy Prime Minister Bulent Arinc saidTurkey was awaiting an explanation from Syria about the downing of the plane, which he said was an unarmed surveillance craft. He called for calmwhile the details were sorted out, saying, “We should not give any credit to provocative acts and statements.”

The episode was another blow to relations between the neighbors, who were close before President Bashar Assad of Syria began his crackdown on protests that started in March 2011, setting off a revolt by political and militia groups now supported by Turkey.

Turkish authorities also suspect Damascus, which was collaborating with Turkey in its fight against autonomyseeking Kurdish rebels, is now turning a blind eye to Syria-based Kurdish fighters who belong to the Kurdistan Workers’ Party, or PKK, which is considered a terrorist organization in the U.S. and Europe.

Turkey, which is uneasy about Greek Cypriot gas exploration efforts around the island, is believed to have increased patrols recently over the eastern Mediterranean. Some analysts have speculated that the plane may have been spying on possible PKK rebels near Turkey’s border.

U.S. Secretary of State Hillary Rodham Clinton earlier this month warned about a massing of Syrian forces near Aleppo, saying such a deployment could be a “red line” for Turkey “in terms of their strategic and national interests.”

Turkey’s prime minister, Recep Tayyip Erdogan, has been one of the most strident critics of Assad’s government and its long crackdown, which has killed thousands.

Since the crackdown, Turkey has allowed more than 32,000 refugees to seek shelter in a string of camps across its 550-mile border with Syria. It has also provided crucial support to dissident groups and the Free Syrian Army, an anti-Assad militia whose leaders live under the protection of Turkish security forces in a fortified camp near the Syrian border.

Germany and Iraq urged the countries to remain calm and not let the unrest in Syria become a wider conflict,

“Our main concern is the spillover of the crisis into neighboring countries. No country is immune from this spillover,” said Iraq Foreign Minister Hoshyar Zebari.

German Foreign Minister Guido Westerwelle said he was “greatly worried,” and urged a thorough investigation while welcoming Turkey’s cool-headed reaction in the immediate aftermath.

United Nations Secretary-General Ban Ki-Moon told Turkey Foreign Minister Ahmet Davutoglu in a telephone conversation Saturday that he commended the country for showing restraint in its initial reaction to the incident, said U.N. spokesman Martin Nesirky. He urged both sides to deal with the issue diplomatically, not militarily.

On Friday, opposition activists reported that as many as 25 men had been shot dead in the village of Daret Azzeh, in northern Aleppo province, in what the activists described as a battle between the Free Syrian Army and members of a pro-Assad paramilitary group.

On Saturday, Al Dunya television, a channel close to the Syrian government, dismissed those claims, saying those killed by the rebels were civilians and not armed fighters.

Opposition activists saidthe bloodshed continued Saturday across Syria, with dozens reported killed in fighting and shelling in Deir el Zour, Homs, Hama, Aleppo, Daraa, Idlib and Damascus and its suburbs. Syria’s restrictions on journalists make it impossible to confirm such reports.

An activist from the Revolutionary Council in Homs estimated that the shelling had wounded 400 people in the city, many of them seriously. He said essential services had been cut off in the city.

Abou Bilal al-Homssi, an opposition activist in Homs, said shelling had deterred the Red Cross from entering the area.

“This is our second week under siege; the humanitarian situation is extremely dangerous,” he said.

In Deir el Zour, near the border with Iraq, at least 22 people were killed Saturday as Syria’s army battled rebels and shelled neighborhoods there, according to the Local Coordination Committees, a network of activist groups in Syria. The victims included women and children, hospital officials said.

In the Tareeq Halab neighborhood of Hama on Saturday, security forces arrested young men and shelled the area, damaging the mosque of Fatima al-Zahraa, a local landmark, said activists with the Local Coordination Committees. The London-based Syrian Observatory for Human Rights, an opposition group with contacts in Syria, said government forces killed at least two people in Hama on Saturday.

The Observatory also reported that the Syrian army on Saturday raided the southern town of Daraa, where the uprising against Assad was born, with tanks, killing one person.

Also on Saturday, Assad announced the formation of a new Cabinet, led by Riad Farid Hijab, a former agriculture minister and a loyalist member of the ruling Baath Party, according to state news media. But the move fell short of a pledge he made last month for a more inclusive government, as crucial ministers kept their positions, including Defense Minister Dawood Rajiha, Interior Minister Mohamed Ibrahim al-Shaar and Foreign Minister Walid al-Moallem.

Information for this article was contributed by Liam Stack, Dalal Mawad, Hwaida Saad and Sebnem Arsu of The New York Timesand by Suzan Fraser, Elizabeth Kennedy, Lara Jakes, Kay Johnson and Juergen Baetz of The Associated Press.

Front Section, Pages 1 on 06/24/2012