The announcement late Friday also said Turkish forces hit Syrian government targets and a number of Syrian troops were "neutralized."

Syrian government forces have been on a weekslong offensive into Idlib province, the country's last rebel stronghold, which borders Turkey. Thousands of Turkish soldiers are deployed inside rebel-controlled areas of Idlib province, which is dominated by al-Qaida-linked militants.

On Thursday, at least 33 Turkish soldiers were killed in airstrikes in Idlib blamed on the Syrian government.

The deaths — the highest number in a single day since Turkey first intervened in Syria in 2016 — were the most serious escalation between Turkish and Russian-backed Syrian forces. It's raised the prospect of an all-out war with millions of Syrian civilians trapped in the middle.

It remained unclear whether Syrian or Russian jets carried out the strike, but Russia denied its aircraft were responsible.

Turkey's President Recep Tayyip Erdogan had given the Syrian government until the end of the month to pull back from areas captured in Idlib, threatening large-scale military action if they didn't. But any large scale Turkish military action risks more loss of life among Turkish soldiers, and it's not clear what Erdogan might do. He's kept unusually silent since the 33 deaths.

Since the start of February, 55 Turkish soldiers have been killed after Turkey began reinforcing its forces in Idlib. It was a bid to thwart the Syrian government offensive, which began in early December.

The Syrian advance into Idlib has pushed nearly 950,000 displaced civilians toward the Turkish border amid cold winter weather.

Meanwhile, in Turkey, refugees had camped overnight beside the border with Greece after hundreds headed to the frontier when Ankara said it would no longer prevent them crossing.

Footage on Turkish television showed dozens of refugees huddled around fires in woods on the border early Saturday. Erdogan, whose country already hosts more than 3.5 million Syrian refugees, has long threatened to "open the gates" for millions to flee to Europe unless more international support was provided.

Greece and Bulgaria increased security at their borders with Turkey as hundreds of people boarded buses in Istanbul, apparently headed for the Greek border or the Turkish coast opposite the Greek islands.

Greek police said an estimated 1,200 people had gathered on the Turkish side of the Kastanies border crossing late Friday and periodically tried to push through. Some managed to cut holes in the border fence close to the crossing and attacked police with stones, but were repulsed with tear gas and stun grenades.

A police officer told The Associated Press that pressure was mounting along the 200-kilometer (125-mile) land border from migrants trying to force their way through, and groups were being constantly repulsed. The officer spoke on condition of anonymity as he was not authorized to speak on the record.

On the border, some of those gathered in the hope of getting into Greece told reporters they had traveled there thinking the border crossing was open, because that was what they had heard on the news and on social media.

NATO envoys held emergency talks Friday at the request of Turkey, a NATO member. While urging deescalation in Idlib, NATO offered no further assistance.

The move by Turkey to open its border is seen in Greece as a deliberate attempt to pressure European countries, and in particular Greece, a fellow NATO ally of Turkey with which frequently testy relations have become increasingly strained.

Erdogan and Russian President Vladimir Putin spoke by telephone Friday and discussed implementing agreements in Idlib, the Kremlin said. Fahrettin Altun, Erdogan's director of communications, said they had agreed to meet "as soon as possible."

Erdogan also spoke with other world leaders, including President Donald Trump and German Chancellor Angela Merkel.

U.N. Secretary-General Antonio Guterres called for an immediate cease-fire in Idlib. He warned that "without urgent action, the risk of even greater escalation grows by the hour, and as always, civilians are paying the gravest price."