Conflicting reports are emerging about the extent of a Turkish military operation across its southern border to chase Kurdish terrorists who operate out of bases in northern Iraq.

According to an Associated Press report that cited two anonymous Turkish security officials, several thousand troops crossed the border in a raid they defined as limited in scope and not constituting the kind of large incursion that Turkish leaders have been discussing in recent weeks.

Reuters quoted another anonymous official who said, "This cannot be called a cross-border operation, it is a limited operation."

But National Security Council spokesman Gordon Johndroe, traveling with President Bush in Rostock, Germany, said the Turkish government reported to the NSC that the reports of a large-scale cross-border incursion are incorrect. Johndroe said U.S. officials in the region have also made their own assessment and concur that no incursion has taken place. Iraqi officials also told Reuters that they saw no such military action.

Turkey has been fighting a Kurdish terrorist group, the Kurdistan Workers Party, or PKK, since the separatists first took up arms in 1984. More than 30,000 people, mostly in southeast Turkey, have been killed in fighting between the militants and Turkish army since that time.

Fighting picked up in intensity in the early-mid 1990s after the U.S. enforced a no-fly zone against then-Iraqi leader Saddam Hussein, who had gassed thousands of Kurdish citizens of Iraq in 1988.

The last major Turkish incursion into northern Iraq was in 1997, when about 50,000 troops were sent to the region. The PKK had gone mostly quiet following the arrest of leader Abdullah Ocalan in February 1999, and Turkey did not allow coalition forces to use its military bases to launch an attack on neighboring Iraq in 2003 for fear of stirring up the rebels.

However, since the liberation of Iraq, Turkey has faced an increase in cross-border skirmishes from the Kurdish militants, newly invigorated by the rising strength of the Kurdish minority as well as general chaos in Iraq. On May 22, PKK, with an estimated 4,000 fighters in northern Iraq, was blamed for planting a bomb in Turkey's capital, Ankara, which left six dead and 80 injured.

One of the officials who spoke to the AP by telephone is based in southeast Turkey. He did not say where the Turkish forces were operating in Iraq nor how long they would be there.

"It is not a major offensive and the number of troops is not in the tens of thousands," the official said.

Iraqi Foreign Minister Hoshyar Zebari said the government has not seen any major operations along the border.

"There has been intermittent shelling, for instance, attacks, certain violations, minor violations on the border which we have documented and reported back to the Turkish side, but honestly we haven't seen any major operations along the border," Zebari told The Associated Press in a telephone interview.

"We are aware of this Turkish troops buildup on the border and the Iraqi government position has been that we will not accept or tolerate any military incursion into Iraqi territories," he said.

Lt. Col. Christopher Garver, a military spokesman in Baghdad, said he could not confirm any Turkish troops were in Iraq but "we are looking into it and obviously we are very concerned."

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.

Wolfgang Piccolo, a security analyst with the D.C.-based Eurasia Group, said the Turkish military is unlikely to launch such an operation because it wouldn't help much to fight the PKK and the United States strongly opposes such a move. On top of that, the secular armed forces, which are at odds with Turkey's ruling Islamic political party, may not want approval for any cross-border operations for fear it could boost that party's electoral appeal ahead of the July 22 elections.

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

The Associated Press contributed to this report.