CUKURCA, Turkey - Turkish fighter jets, helicopters and hundreds of commandos streamed across the border into northern Iraq Wednesday despite Iraqi and American calls to swiftly end an operation to root out Kurdish insurgents.

U.S. Defense Secretary Robert Gates said before departing for Turkey that he will tell officials there that the six-day assault must not last longer than a week or two.

It was the first time that Gates, who that Turkey must be "mindful of Iraqi sovereignty," put any time limit on the incursion.

Gates also said before leaving India that he will call on Turkey to use economic and political initiatives to address some of the complaints of the Kurds -- who are the majority in Turkey's southeast and neighboring northern Iraq. Iraq has demanded an immediate end to the cross-border operation against the Kurdistan Workers' Party, or PKK.

In Baghdad, Turkish envoy Ahmet Davutoglu, chief foreign policy adviser to Prime Minister Recep Tayyip Erdogan, said the aim of the incursion was "clear and limited" and said no timetable will be set "until the terrorist bases are eliminated."

More than 40 Turkish military trucks ferried hundreds of commandos toward the Iraqi border and F-16 warplanes were seen flying over the border town of Cukurca toward Iraq. Helicopters brought dozens of troops to a base on the outskirts of the town. Some helicopters also headed toward Iraq.

Iraqi Foreign Minister Hoshyar Zebari said after meeting Davutoglu that, "We condemn the terrorists and the PKK, but we also condemn the violations of the sovereignty of Iraq at the same time and we have to be very clear on that."

Turkey said its troops had killed 77 Kurdish rebels in overnight clashes that were the most intense of the incursion in northern Iraq. Five soldiers were also killed.

The remote battle sites are inaccessible to the press and casualty reports cannot be independently confirmed.

The total death toll for the rebels since the operation began Feb. 21 reached 230, the military said. Two dozen soldiers and three pro-government village guards also have been killed.

PKK spokesman Ahmad Danas denied the Turkish military's claim that 77 Kurdish rebels had been killed in the overnight clashes, saying the rebels had only lost one fighter since Tuesday night and seven others were wounded. The rebels have said only a few PKK fighters and more than 80 Turkish soldiers have died.

It is the first confirmed Turkish military ground operation in Iraq in about a decade against the rebels, who are fighting for autonomy for southeastern Turkey and have carried out attacks from northern Iraq. The conflict has killed up to 40,000 people since 1984. The U.S. and European Union consider the PKK to be a terrorist group.

The Turkish military said warplanes have hit 225 targets, including anti-aircraft batteries, caves, shelters, training facilities, command and communication centers, while artillery units struck 475 similar targets.

"There are sporadic clashes with terrorists that arrived as reinforcements to the region in two separate areas on the sixth day of the operation," the military said on its Web site.

"There are signs that some high-level names of the organization might still be among terrorist groups in the (combat) zone," it said. In past operations, the military has monitored radio communications of rebels.

Turkey has long suspected the Iraqi Kurd administration in the north of allowing the PKK to operate and ignoring calls for a crackdown on the group. Turkey's military said this week that it had received information that some wounded rebels were being treated in hospitals in northern Iraq.

The Kurdish regional government in northern Iraq denied the allegations.

"We challenge anyone who says that PKK wounded fighters are receiving treatment in our hospitals," spokesman Jamal Abdullah said. "We have nothing to do with PKK fighters and routes to areas where clashes are taking place are closed."

Turkish Kurds protesting the incursion in the eastern town of Dogubayazit threw stones at the local branch of the ruling party as well as the main police station, NTV television showed. Police used tear gas to disperse the crowd, it said.