BEIRUT, Lebanon — Turkish soldiers were killed on Thursday by Syrian warplanes while fighting inside Syria for the first time since the civil war there began in 2011, the Turkish military announced.
Three soldiers were killed and 10 others wounded, the military said. The troops were advancing toward Al Bab, a city in the north held by the Islamic State, close to the border with Turkey.
The announcement heightened the tensions between Syria and Turkey, neighboring countries that have powerful allies.
The Syrian government is backed by Russia and Iran. Turkey, a member of NATO, began a major offensive in northern Syria in August as part of its fight against the Islamic State.
Syrian Arab rebel forces fighting with the Turks said they had not received official notification that the Syrian government had launched the strike. One fighter said he had heard that the strike was from the Syrian government but heard later that it had been from the Islamic State. The Syrian Observatory for Human Rights, a network based in Britain that monitors news from Syria, also said that the strike had been by the Islamic State.
Like Turkey, the Syrian rebels, who receive aid from the Pentagon, oppose the government of the Syrian president, Bashar al-Assad.
The Turkish troops had gone into Syria in large part to try to stop an advance by Kurdish rebels who are also trying to reach Al Bab to dislodge the Islamic State. The Turkish authorities see the Kurds as a threat to security as serious as the Islamic State, in part because Kurdish groups inside Turkey have waged a guerrilla war against the Turkish government.
Ankara wants to stop the Kurds from reaching the city in part because, if the Kurds succeed, it will enable them to gain a portion of the land that sits between two Kurdish-held areas along the Syrian-Turkish border.
On Thursday morning, Turkish troops, backed by Syrian Arab fighters, had almost reached Al Bab, according to rebel commanders. They said they were a little more than half a mile from the city when they were hit by the government jets.
Although this is the first time that the Turkish military has reported the deaths of its soldiers by Syrian government planes, Turkish troops have died while fighting the Islamic State in Syria.
Also on Thursday morning, a car packed with explosives blew up in the parking lot of the governor’s office in the southern Turkish city of Adana, shaking buildings for blocks around, according to local news reports. Two people were killed and 21 others wounded, according to government estimates.
The Turkish newspaper Hurriyet’s website quoted Mahmut Demirtas, the governor of Adana, as saying that a vehicle had exploded at about 8 a.m. in the parking lot, close to the entrance that is used by high-level officials in the city government.
No one has claimed responsibility for the blast.