A US State Department official held direct talks for the first time last weekend with a Syrian Kurdish group involved in the fight against Islamic State in Syria, including the besieged town of Kobani, the State Department said on Thursday.
Following the talks, the last three days saw an upsurge in US air strikes on Islamic State forces besieging the town, and Kurdish spokesmen said their forces were giving coordinates of the militants' positions to the United States.
"We have for some time had conversations through intermediaries with the PYD (Democratic Union Party). We have engaged over the course of just last weekend with the PYD," State Department spokeswoman Jen Psaki said in Washington.
A senior administration official said the talks, which involved a State Department official, took place in Paris.
News of the talks raised questions about the position of Turkey, which distrusts the PYD, the main Kurdish political organisation in Syria, because of its affiliation with the PKK, the Kurdish group that has fought for autonomy in Turkey.
The United States has been trying to persuade Ankara to take a greater role in the campaign against Islamic State, which has taken control of large areas of northern Iraq and Syria, including territory along Turkey's southern border.
US and Turkish military officials held talks this week in Ankara to discuss details of what Turkey will do, and a Pentagon spokesman on Thursday said they had gone "very, very well."
"The discussions were positive, we think our team's coming away with, I think, a general good report here, but I wouldn't get ahead of anything Turkey may or may not do," Rear Admiral John Kirby told reporters.
Turkey has taken a hard line against the PKK in recent days, adding further turmoil to the conflict in the region.
On Tuesday its warplanes attacked PKK targets, risking reigniting a three-decade conflict that killed 40,000 people before a cease-fire was declared two years ago.