Several thousand Turkish troops crossed into northern Iraq early Wednesday to chase Kurdish guerrillas who operate from bases there, Turkish security officials told The Associated Press.

Two senior security officials, speaking on condition of anonymity because they were not authorized to speak to the media, said the raid was limited in scope and that it did not constitute the kind of large incursion that Turkish leaders have been discussing in recent weeks.

"It is not a major offensive and the number of troops is not in the tens of thousands," one of the officials told the AP by telephone. The official is based in southeast Turkey, where the military has been battling separatist Kurdish rebels since they took up arms in 1984.

The officials did not say where the Turkish force was operating in northern Iraq, nor did they say how long they would be there.

The officials said any confrontation with Iraqi Kurdish groups, who have warned against a Turkish incursion, could trigger a larger cross-border operation. The Turkish military has asked the government in Ankara to approve such an incursion, but the government has not given formal approval.

Military official won't confirm report

An official at military headquarters in Ankara declined to confirm or deny the report that Turkish troops had entered Iraq.

Meanwhile, the White House denied the report. Speaking to Reuters from the G8 summit in Germany, White House officials said there was "no new activity" from Turkish troops in northern Iraq.

Turkish troops have occasionally launched brief raids in pursuit of guerrillas in northern Iraq, and have sometimes shelled suspected rebel positions across the border. Turkish authorities rarely acknowledge such military operations, which were more frequent before the U.S.-led invasion of Iraq in 2003.

Turkey has been building up its military forces on the Iraqi border in recent weeks, amid debate among political and military leaders about whether to attack separatist rebels of the PKK, or Kurdistan Workers' Party. The rebels stage raids in southeast Turkey after crossing over from hideouts in Iraq.

During major incursions in the 1990s, fighting occurred on a front stretching more than 161 kilometres, mostly in rugged terrain where communications were difficult and the Turkish Kurds were already entrenched in the mountains.