ISTANBUL — Turkey amplified the big-power tensions over the increasingly chaotic war in Syria on Tuesday, saying it is in discussions with allies, including the United States, over collaborating on a military ground operation into northern Syrian territory.

A Turkish official who spoke to reporters in Istanbul about the Syrian situation said that it was now impossible to halt the war without a ground operation in northern Syria, and that the Turks would not undertake such an operation on their own.

“We are asking coalition partners that there should be a ground operation,’’ said the official, who was authorized to speak on the condition that he not be identified by name. “We are discussing this with allies.’’

While it was unclear how far the discussions have progressed, it appeared unlikely that a ground operation would be mounted. Saudi Arabia has said it would be willing to commit troops, but the United States has repeatedly indicated that it would not.

A ground operation could put US and Russian forces at risk of a direct military confrontation for the first time in the nearly five-year Syria war, even as both Russia and the United States say they are working toward the “cessation of hostilities’’ called for in a diplomatic agreement reached last week in Munich.

Syrian forces backed by Russian airstrikes have achieved some of their biggest gains in the conflict in recent days, driving insurgents out of their enclaves in northern Syria and advancing in some places to within 15 miles of the Turkish border.

The Syrian advances have been exploited by Kurdish militants in northern Syria to expand their territory, upsetting the Turkish authorities, who see an immediate threat from the Kurds, their longtime adversaries.

New York Times