Wednesday's meeting was the highest-level encounter reported between the sides since the start of the Syrian war more than a decade ago. Turkey has played a major part in the conflict, backing President Bashar al-Assad's opponents and sending troops into the north.

The rapprochement, brought about with encouragement from Assad's most powerful ally Russia, could reshape the war. But obstacles include the fate of rebel fighters backed by Turkey and that of millions of civilians, many of whom fled to the Turkish border to escape Assad's rule.

The Turkish official described the meeting as "positive".

That echoed a Syrian defense ministry statement issued after the meeting, which was also attended by the Russian defense minister and the Syrian and Turkish intelligence chiefs, who have met repeatedly in recent months.

"It was discussed how the Turkish side can act jointly against terrorist organizations such as (the Kurdish) YPG and Daesh in order to ensure the territorial integrity of Syria and the fight against terrorism," the Turkish official told Reuters, speaking on condition of anonymity as he was not authorized to speak publicly on the matter.

"It was emphasized that Turkey's priority is border security."

Badran Jia Kurd, a senior official in the Kurdish-led autonomous administration of northern Syria, said he expected "a new phase of deals and plans ... hostile to the interests of Syrians" to develop from the meetings.

Speaking to Reuters, he expressed concern this would "strike the gains made by our people in northern and eastern Syria".

Turkey has mounted three incursions into northern Syria largely aimed at the Syrian Kurdish group the YPG, which established autonomy over much of the north as the war began in 2011.

Turkey views the YPG as a national security threat because of its ties to the militant Kurdistan Workers' Party (PKK), and has been threatening another incursion since a deadly bomb attack in Istanbul last month.

Both Russia and the United States, which has partnered with the Kurdish-led Syrian Democratic Forces in fighting Islamic State in Syria, have objected to this.

Notwithstanding occasional clashes, the YPG and Damascus have largely stayed out of each other's way during the war and have shared foes, including Turkey-backed groups.

But Damascus opposes Kurdish autonomy demands, and talks for a political settlement have made no progress.

Turkish-Syrian rapprochement seemed unthinkable earlier in the conflict, which has killed hundreds of thousands of people, drawn in numerous foreign powers, and splintered Syria.

Turkish President Tayyip Erdogan has called Assad a terrorist and said there could be no peace in Syria with him in office, while Assad has called Erdogan a thief for "stealing" Syrian land.

Al-Watan, a pro-Syrian government newspaper, cited sources saying the defence ministers' meeting would not have happened "if matters had not been moving in an acceptable way and according to what Damascus wanted" during previous meetings.

Syrian state news agency SANA, citing its correspondent, said the sides discussed "efforts to combat terrorism, the situation in Syria, and the question of refugees" at the meeting.

The three ministers affirmed "the importance of continuing the joint dialogue for the sake of stability of the situation in Syria and the region", SANA added.

The Turkish official also said it was emphasized at the meeting "that immigration from Syria to Turkey was no longer welcome". Turkey hosts at least 3.7 million Syrian refugees, the world's largest refugee population. Public sentiment turned somewhat against the refugees as Turkey's economic woes mounted.

"The first goal will be to build trust. Both sides will be looking for wins," said Huseyin Bagci, professor of international relations at Middle East Technical University, Ankara, calling the meeting "an important step towards normalization".

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