US President George W Bush has urged Turkey to complete its military operation in northern Iraq swiftly.
The Turkish military says it wants to destroy PKK bases
Mr Bush told a news conference, he said the Turks needed to "move quickly, achieve their objective and get out."
Turkey sent troops into Iraq last week in an operation it said was aimed at getting rid of PKK Kurdish rebel bases.
It says 237 rebels and more than 20 soldiers have been killed so far. The PKK says it has killed more than 100 soldiers. There is no confirmation.
Mr Bush dismissed suggestions that Turkey should be threatened with the removal of American intelligence co-operation.
"The key for us is to make clear what our interests are, our concerns about the situation in Iraq," he said.
Mr Bush's comments followed an earlier statement by US Defence Secretary Robert Gates during a visit to Turkey.
Turkey's incursion into northern Iraq "should be as short and precisely targeted as possible", he said after talks with his Turkish counterpart Vecdi Gonul in the capital, Ankara.
Mr Gonul said the assault on the PKK separatists, who want an independent homeland in south-east Turkey, would last "as long as necessary".
In the latest fighting, a PKK spokesman was quoted as saying heavy clashes broke out when rebels surrounded 200 Turkish soldiers in a mountain valley.
Iraq says the incursion, launched last Thursday, is unacceptable and violates its sovereignty.
Since November, the US has been providing real-time intelligence to help Turkey target the PKK across the border.
Ankara will not want to jeopardise that vital support, the BBC's Sarah Rainsford in Istanbul says.
But now that Turkish troops are engaging the PKK on the ground, apparently successfully, the military will not be keen to leave too soon either, our correspondent says.
More than 30,000 people have been killed since the PKK its campaign in 1984.