The U.S. military said Thursday it had no evidence to substantiate a report that Iranian troops have been building a small fort on Iraqi territory since crossing the border in pursuit of Kurdish rebels.

The Los Angeles Times on Wednesday cited Kurdish officials who said that a small Iranian force crossed into the Kurdish-controlled region a week ago after a bomb attack that killed several Iranian soldiers.

The Kurdish regional government's defense spokesman, Jaber Yawer, told the newspaper that about 35 Iranians remained behind in an area near the Perdunaz border crossing, and have since been observed building a fortified structure high on a mountain.

"We have no evidence they have constructed forts or fortified positions within Iraqi territory," Major General Stephen Lanza, chief spokesman for U.S. forces in Iraq, said Thursday in a conference call.

"Right now we have no evidence that they have actually crossed," he said.

"What we would hope is that
Iraq and Iran work out the issues of border operations," he said.

"And obviously the insurgents that you talk about or the militia forces that you talk about, whether they are PKK or PJAK, is something that will have to be resolved between all the governing parties here."

PJAK is the acronym for Party for Free Life in
Kurdistan , an Iranian Kurdish militant movement that allegedly carried out the attack on the Iranian troops.

The PKK is the Kurdish Workers' Party, a Kurdish separatist group fighting for independence of Kurdish areas in
Turkey .

Tensions have flared up since a PKK rocket assault May 31 on a Turkish naval base that left six soldiers dead. On Monday, there were unconfirmed reports of that Turkish warplanes bombed several Kurdish positions in northern
Iraq .