ISTANBUL — Turkey’s foreign minister said Sunday that his country would hold emergency talks with NATO in the next few days over the downing of one of its jet fighters by Syria, claiming the plane was attacked in international airspace.

“Next week, Permanent Council of NATO will be informed,’’ Foreign Minister Ahmet Davutoglu said in a Twitter message posted from his official account on Sunday.

In another posting on Sunday, Davutoglu said that Turkey, a NATO member, would invoke Article 4 of the NATO treaty, which provides for consultations by the allies when one is attacked or threatened. He did not cite the much stronger Article 5, in which an attack on one member is considered an attack on all NATO countries and obliges a concerted response.

Davutoglu posted the messages after he told state-owned TRT TV that the Turkish authorities’ analysis of radar, visual, and communications data had confirmed that their aircraft was struck by Syrian antiaircraft weapons outside of Syrian airspace.

‘‘Our plane was hit in international airspace, 13 nautical miles out of Syria, when Syrian territorial space is 12 miles,’’ he said. He said that the Turkish investigation had left no doubt that the aircraft, a two-seat F-4 Phantom, had briefly strayed over Syria but had been shot down after leaving its territory.

The television network reported that the aircraft’s wreckage and its ejection seats had been found on Sunday in the Mediterranean Sea off the Syrian coast. The search continued for the crewmen, the report said.

Secretary of State Hillary Rodham Clinton sharply criticized Syria for downing the Turkish plane. ‘‘The United States condemns this brazen and unacceptable act in the strongest possible terms,’’ she said. ‘‘It is yet another reflection of the Syrian authorities’ callous disregard for international norms, human life, and peace and security.’’

Clinton said Washington will maintain close contact with Turkish officials as they determine their response, including via the UN Security Council.

In Brussels, the NATO spokeswoman, Oanu Lungescu, told Turkey’s Anatolia News Agency that the allies would meet on Tuesday to discuss the downing of its jet.

Syria has said it shot down the plane because it was flying low into its airspace and appeared to have hostile intentions. ‘‘It was an accident, certainly not an attack,’’ the Syrian foreign minister, Jihad Makdissi, told the Turkish news channel A Haber on Saturday.

Davutoglu said the Turkish jet was on a training exercise. He said the aircraft was flying alone, without weapons, and that the Syrian authorities had made no attempt to contact it. When the Turkish authorities realized it had strayed into Syrian airspace, the pilots were warned to leave and did so immediately, Davutoglu said. Minutes later, the Syrians fired on the plane, he said.

Turkey had not yet decided what action to take, the foreign minister said.

Prime Minister Recep Tayyip Erdogan of Turkey met with his military chiefs on Saturday, his third crisis meeting since the downing of the jet on Friday. Erdogan has so far been circumspect in his response to the episode.

On Sunday, however, Davutoglu’s Twitter feed suggested a hardening of Turkey’s stance toward Syria.

‘‘No one should try to test the capacity of Turkey,’’ he wrote. He added that Turkey had discussed the matter with Russian and Chinese officials, who praised its ‘‘calm approach.’’

The violence continued in Syria on Sunday, with the Syrian Observatory for Human Rights, which is based in London, reporting that 38 people were killed around the country; the Local Coordination Committees, a grass-roots group in Syria, said 43 had died.

The committees said 14 of the victims were in Deir el-Zour, a city in eastern Syria. Eight were reported killed in the western city of Idlib, near the Turkish border. In Aleppo, Syria’s largest city, seven died, according to the committees.

Earlier Sunday, activists said rebel fighters captured a military base in the northern Syrian province of Aleppo, confiscating large amounts of ammunition, the Associated Press reported. The Observatory said 16 government troops died in the attacks on the base near the rebel-held town of Daret Azzeh and nearby checkpoints.