Turkish warplanes have bombed suspected Kurdish rebel hideouts in northern Iraq for the fourth time in five days. There are no immediate reports of casualties.

The Turkish military says the aircraft hit eight caves and hideouts used by Kurdistan Workers' Party (PKK) rebels Wednesday in Iraq's Dahuk province.

Turkish state media quote President Abdullah Gul as saying that Ankara and Washington are satisfied with their cooperation in sharing intelligence to fight the PKK.

A White House spokesman reiterated today that the United States regards the PKK as a terrorist group. But, he says the Bush administration has expressed concern to Ankara about any steps that could lead to civilian casualties.

Turkish soldiers patrol on a road near Yuksekova, southeastern Turkey near the border with Iraq, 26 Dec 2007

In another development, the Turkish military says troops killed six PKK rebels and captured two others Wednesday in a security operation in southeastern Turkey, near the Iraqi border.

It says troops have killed 11 rebels in the operation in Sirnak province since Tuesday.

The military said Tuesday that it has killed at least 150 to 175 Kurdish rebels in northern Iraq since December 16, when it began cross-border bombing raids. There has been no independent verification of rebel casualties.

Ankara had threatened to attack PKK bases in northern Iraq in response to a series of deadly ambushes by the group in southeastern Turkey in recent months. The Turkish parliament authorized cross-border operations against the group in October.

The PKK has been fighting for self-rule in southeastern Turkey since 1984. The conflict has killed more than 30,000 people.