Turkish troops crossed into northern Iraq early Wednesday to chase Kurdish guerrillas who attack Turkey from bases there, three Turkish security officials said. Turkey's foreign minister denied its troops had entered Iraq.

Turkish military trucks carry tanks towards the Iraqi border, in the southeastern Turkish town of Mardin, May 30 2007. [Reuters]

The senior security officials, speaking on condition of anonymity because they were not authorized to speak to the media, characterized the raid as a "hot pursuit" raid that was limited in scope. They told The Associated Press it did not constitute the kind of large incursion that Turkish leaders have been discussing in recent weeks.

One official said several thousand troops went less than two miles inside Iraq and were still there in late afternoon. "It is a hot pursuit, not an incursion," one official said.

Another official said by telephone it was "not a major offensive and the number of troops is not in the tens of thousands." He also said the Turkish troops went into a remote, mountainous area.

A third official, based in the border region, said 600 commandos entered Iraq, and were backed up by several thousand troops along the border. He said the commandos raided Iraqi territory across from the Turkish border town of Cukurca before dawn after rebels opened fire from Iraqi soil on Turkish patrols.

The official said the commandos returned to their bases in Turkey later in the day. There was no immediate explanation for the conflicting accounts of the officials.

All three officials are based in southeast Turkey, where the military has been battling separatist Kurdish rebels since they took up arms in 1984.

The officials stood by their statements despite denials from Turkish and Iraqi officials.

Turkey's private NTV television quoted Foreign Minister Abdullah Gul as saying reports of a cross-border operation were false.

"There is no such thing, no entry to another country. If such a thing happens, then we would announce it," Gul said. "We are in a war with terror, we will do whatever is necessary to fight terrorism."

Several military officials at the Pentagon said they have seen nothing Wednesday that would confirm the reports of Turkish troops crossing the border into Iraq.

One military official said that small numbers of Turkish forces periodically move in and out of Iraq doing counterinsurgency operations, but not thousands at one time. The officials requested anonymity because of the sensitivity of the information.

While the U.S. has about 16,500 troops in northern Iraq, most of them are not right along the border. Many of those are training teams working with the Iraqi border patrols.

The White House said there has been "no new activity" in northern Iraq to justify the press reports. Gordon Johndroe, a spokesman for the White House's National Security Council, said that U.S. officials in the region have confirmed that the activity is a continuation of Turkey's years-long campaign against the Kurdish PKK guerrillas of Kurdistan Workers' Party.

"The Turkish government reports no new incursions into northern Iraq," Johndroe said. "U.S. officials on the ground confirm no new activity."

Johndroe said Washington remains "concerned about the PKK and the use of Iraq as a safe haven."

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 last major Turkish incursion into northern Iraq was in 1997, when about 50,000 troops were sent to the region.

The officials did not say where the Turkish force was operating in northern Iraq, nor did they say how long they would be there. Both officials are involved in anti-rebel operations, though they did not disclose whether they participated in the planning of the operation on Wednesday.

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.

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

Turkish authorities rarely acknowledge such military operations, which were more frequent before the U.S.-led invasion of Iraq in 2003.

Earlier Wednesday, reports of an incursion circulated on some media outlets, including Turkey's private Cihan news agency.

The Turkish military said rebels across the border in Iraq opened fire Wednesday on a Turkish military outpost in the province of Hakkari, which borders both Iraq and Iran. It said there were no casualties.

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

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.

During major incursions in the 1990s, fighting occurred on a front stretching more than 100 miles, mostly in rugged terrain where communications were difficult and the Turkish Kurds were already entrenched in the mountains.