Turkey Sunday accused Syria of shooting down a Turkish military jet in international airspace and called for a NATO meeting on how to respond to Syrian President Bashar al-Assad.

Turkish Foreign Minister Ahmet Davutoglu said the pilots were testing the jet's radar capabilities when it was downed Friday over the Mediterranean Sea. The minister said the plane had entered Syrian airspace briefly, but had left about 15 minutes before it was shot down. Syrian and Turkish forces still are searching for the two missing pilots.

At Ankara's request, NATO officials say the alliance will meet Tuesday under Article 4 of its founding treaty, which commits all members to protect one anothers' security and borders.

Syria has acknowledged downing the plane, saying it trespassed on Syrian airspace. Syrian authorities said they shot down the jet in accordance with laws that govern such situations.

Relations between Turkey and Syria are tense, with Turkey condemning Syria's bloody crackdown on protests against the government of President Assad. Meanwhile, Damascus has accused Ankara of providing weapons and intelligence on its forces to Syrian rebels.

Turkey maintains that its plane was not involved in any covert activities.

Opposition activists in Syria say government forces and rebel forces continued to clash Sunday across the country, leaving some 40 people dead.

Turkey has joined nations such as the United States in saying President Assad should step down because of the uprising in his country.