Turkish artillery shelled suspected Kurdish rebel positions across the border in northern Iraq, Iraqi Kurd officials said Friday, and U.S. Secretary of State Condoleezza Rice warned Turkey that it risked expanding regional tensions with any "robust" move of troops into Iraq.

Turkey has been building up its forces along the border with Iraq and its leaders are debating whether to stage a major incursion to pursue separatist rebels who cross over from bases in Iraq to attack Turkish targets. Such an operation could ignite a wider conflict involving Iraqi Kurds, and draw in its NATO ally, the United States.

Rice, speaking in New York to a panel of journalists and editors from The Associated Press, said it's "not good for anybody for a robust move across the border." She described it as "not good for Iraq and not good for Turkey."

The statement by Rice suggested that Washington has acknowledged that Turkey might conduct limited incursions across the rugged frontier against the separatist Kurdistan Workers' Party, also known as PKK.

Iran has also clashed with Iranian Kurd fighters who have bases in remote, mountainous areas of northern Iraq, and Iranian forces reportedly participated in the overnight shelling.

The Patriotic Union of Kurdistan, or PUK, the party of Iraqi President Jalal Talabani, reported the Turkish and Iranian shelling on its Web site. Turkish military authorities at the General Staff in Ankara were not immediately available for comment.

Iranian officials in Tehran could not immediately be reached for comment late Friday. Iranian media contained no reports on any shelling, and usually wait several days to report such incidents.

The PUK said artillery shells overnight hit some areas in the Sidikan area in Irbil province, where the borders of Turkey, Iran and Iraq converge, and that nine villages were affected. It was unclear whether there was any degree of coordination among Turkish and Iranian gunners.

"Huge damage was inflicted on the area," the PUK said, citing what it described as an unidentified "source" in the area. "The source said that residents have left their houses, fearing for their lives."

Lt. Ahmed Karim of the Iraqi border guards force told The Associated Press that seven Turkish shells landed on a forest near Sakta village in the Batous area, but no casualties were reported.

A senior official in the Kurdistan Democratic Party, the party of the region's leader Massoud Barzani, confirmed there had been Turkish shelling of Iraqi territory, but declined to give details.

"The situation is unclear and we do not have details about the shelling," said the official, Sarbest Yazkin.

Turkey's military on Friday declared its "unshakable determination" to defeat Kurdish rebels, and a fourth soldier died of injuries from a roadside bomb in a new Turkish security zone north of the Iraq border. The bombing Thursday was blamed on Kurdish separatists.

On Wednesday, Turkish security officials and an Iraqi Kurdish official said Turkish soldiers had crossed into Iraq in pursuit of rebels based there. Foreign Minister Abdullah Gul denied such a raid took place.

Turkish forces occasionally have pursued Kurdish rebels just across the border, but rarely announce the operations.

Turkey has restricted access to large swaths of border territory where its force buildup is occurring. A major incursion would have greater political ramifications than pursuits, and Turkish leaders say it would require parliamentary approval.

The Turkish officials who spoke to The Associated Press about Wednesday's raid did so on condition of anonymity because they were not authorized to speak to the media. One of them said 600 commandos took part, and returned to Turkey by the end of the day.

An Iraqi Kurd official who spoke on condition of anonymity said Turkish soldiers had crossed the border on Wednesday chasing guerrillas hours after the military said rebels had fired from across the frontier near the Turkish border town of Cukurca.

Some Iraqi government officials also denied the report of the raid, and U.S. officials said they could not confirm it.

Turkish leaders say the guerrillas cross into Turkey to stage attacks in their recently escalated fight to win autonomy for southeastern Turkey, where ethnic Kurds make up much of the population.

U.S. officials have argued against a major Turkish incursion into northern Iraq, one of the few spots of relative stability in the country. Some think Turkey may hope its military buildup will push the United States and Iraqi Kurds to crack down on the separatists and head off a Turkish offensive.

The military has announced new "temporary security zones" along the Iraq border. It said the zones would be in place until Sept. 9, but gave no other information.

Turkish media said the areas would be closed to civilian plane flights, and that additional security measures would be implemented in the zones and entry would be restricted.