Gates, who is scheduled to meet Thursday with Turkish President Abdullah Gul and Prime Minister Recept Tayyip Erdogan, said he would personally tell Turkish leaders they should end the offensive against Kurdish PKK separatists as quickly as possible.

"I measure quick in terms of days, or a week or two, something like that. Not months," he told reporters in New Delhi before departing for Turkey, his last stop in a trip that has also taken him to Indonesia and Australia.

Tension has mounted as the Turkish assault against Kurdish separatists in northern Iraq dragged into a sixth day with the Turkish military reporting 77 members of the Kurdistan Workers Party, PKK, killed in heavy overnight fighting.

A senior Turkish official said the operation would continue until the PKK, listed as a terrorist group by Turkey and the international community, is uprooted from the region, which it uses a springboard for attacks in Turkey.

"There will be no timetable to withdraw Turkish troops... until the presence of the terrorist organisation is eliminated," said Ahmet Davutoglu, chief foreign policy advisor to Prime Minister Recep Tayyip Erdogan.

Davutoglu, accompanied by two other officials, was dispatched to Baghdad as Ankara sought to allay mounting Iraqi protests over the incursion.

"We condemn terrorism. We condemm the PKK but at the same time we condemn any violation of Iraqi sovereignty," Iraqi Foreign Minister Hoshyar Zebari said after talks with the delegation.

While Washington has expressed understanding for the Turkish position, and still shares near real-time targeting intelligence with it on the PKK, it also appears to be growing impatient with Ankara.

Gates said he will personnally tell Turkish leaders they should quickly end the offensive.

"I will make that point but I must say it has been manifest by any number of senior officials pretty straightforwardly to the Turks," Gates said in New Delhi.

"I also will repeat the point that I made to (Turkish) President Abdullah Gul when he visited Washington, which is that military activity alone will not solve this terrorist problem for Turkey," he said.

A senior US defence official travelling with Gates said officials had debated whether to drop Ankara from the secretary's schedule as a message to the Turks.

"After a short discussion, everbody decided it was best to go and engage the Turks personally," the official said, speaking on condition of anonymity.

Gates' biggest lever over Turkey is access to US intelligence from dedicated US surveillance and reconnaissance assets trained on the PKK.

A US decision to suspend the intelligence sharing would be a significant loss for the Turks and could also result in operations that were less precise and more prone to civilian casualties.

Gates has emphasized that the Turks should shift from military action, which tends to become less effective over time, to a more comprehensive strategy that aims to take away public support for the PKK among Kurds.

"There certainly is a place for security operations, but these also need to be accompanied by economic and political initiatives, and to deal with some of the issues that provide a favorable local environment where the PKK can operate," he said.

"They need to deal with some of the issues and complaints that some of the Kurds have and move this in a non-military direction in order to get a long term solution," he said.

He said the United States would considering helping Ankara with such an approach if asked.