The Pentagon promised to keep supplying its NATO partner with intelligence to "deal with" the outlawed Kurdistan Workers' Party (PKK), while the White House called the group "a threat" to Turkey, the United States and Iraq.

US President George W. Bush kept quiet on the issue, and his chief spokeswoman, Dana Perino, repeatedly insisted that "conflicting reports" about the assault made it impossible to comment in detail.

"There are conflicting reports in terms of the depth and scope and breadth of it," said Perino, who made clear she was not challenging reports that Turkish ground troops had entered Iraq's autonomous Kurdish region.

"Well, they have, but they have been doing that for years. That's a new operation yesterday, but it's not new over the course of time," she told reporters. "This is an issue that's been going on for some while."

"We've asked Turkey to be very limited in its activities and we certainly have cautioned, as Secretary (of State Condoleezza) Rice said today, very concerned about any loss of innocent life," said Perino.

Rice herself appeared to suffer a diplomatic snub in response to perceived US approval of Turkish air attacks on the PKK last week, with Kurdish regional President Massud Barzani refusing to meet with her as she stopped in Baghdad.

"He will not go now as a sign of protest against the American position on the bombings by Turkey," Kurdish regional Prime Minister Nechirvan Barzani said. "It is unacceptable that the United States, in charge of monitoring our airspace, authorized Turkey to bomb our villages," he said.

Barzani's office said in a statement that around 500 Turkish soldiers entered northern Iraq and remained in remote areas along the Iraq-Turkey border before beginning a withdrawal. Turkey declined to confirm the incursion.

"No-one should do anything that threatens to destabilize the north," Rice said during a joint public appearance with Iraqi Foreign Minister Hoshyar Zebari.

But White House and Pentagon officials made clear that Washington, which effectively controls Iraqi airspace, would continue to support Turkey's campaign against the PKK.

"I can tell you that of course we are coordinating with the Turkish and Iraqi authorities in the area. The PKK is a threat to Turkey, to Iraq, and to the United States. So we continue to share information, share intelligence, with them (Turkish and Iraqi authorities)," said Perino.

"The Turks have moved forward with our coordination and in communication with the Iraqis in order to eradicate that threat," the spokeswoman said.

"The United States is going to continue to provide assistance in terms of information that would be helpful to Turkey to deal with this terrorist threat," said Pentagon spokesman Bryan Whitman.

In the past, US officials have cautioned Turkey, albeit tepidly, against ground strikes at the PKK, which is branded a terrorist group by the United States, Europe and Turkey.

On October 22, Rice spokesman Sean McCormack declared that "we do not believe unilateral cross-border operations are the best way to address this issue."

And Rice, referring to air strikes on Sunday, said Tuesday that "we continue to be concerned about anything that could lead to innocent civilian casualties or to a destabilization of the north."

burs-ok/pmh