Serkan Senturk, Associated Press
A pro-Kurdish demonstrator holds candles in Istanbul, Turkey, Wednesday, protesting Turkey's pursuit of guerrillas in Iraq.

BAGHDAD — U.S. Defense Secretary Robert M. Gates urged Turkish leaders on Wednesday to abandon their invasion of guerrilla-controlled lands in the northernmost reaches of Iraq by mid-March.

U.S. and Iraqi leaders seem increasingly worried that fighting along the Turkey-Iraq border could widen into a broader and bloodier conflict.

"It's very important that the Turks make this operation as short as possible and then leave," Gates told reporters in New Delhi on Wednesday as he prepared to leave for Turkey.

His words reflected the Bush administration's sharper tone toward the Turkish government over the cross-border raids and stood in contrast to earlier U.S. statements backing the Turks in their operations against guerrillas from the Kurdistan Workers' Party, known as the PKK, the initials of the group's name in Kurdish.

"I measure quick in terms of days, a week or two, something like that, not months," Gates said. It was the first time he had demanded a strict timeline for the Turkish operation to end.

The Turkish military has vowed to destroy the havens inside Iraq that PKK fighters have long used to stage attacks and assassinations in Turkey. Last week, the Turks launched their most ambitious operation against the guerrillas in years, with what Turkish media reports described as thousands of troops.

Turkey claims that it has killed 230 PKK guerrillas since last Feb. 21, including 77 rebels killed since Tuesday. Ahmed Denis, a PKK spokesman, scoffed at the Turkish numbers and said more than 100 Turkish soldiers had been killed. Neither claim could be independently verified.

U.S. officials have supported the right of Turkey, a crucial NATO ally, to defeat the PKK, which the United States classifies as a terrorist organization. The United States has also been providing intelligence to the Turks about the guerrillas.

Turkey has sometimes sent troops over the border in temporary "hot pursuit" raids against guerrillas. But this is the first time that U.S. officials have been so adamant about urging a Turkish withdrawal.

Though the Turkish invasion has been limited so far, Iraqi officials say they fear what it could become. The Iraqi Cabinet issued a statement on Tuesday night condemning the operation as a violation of Iraqi sovereignty and warning that "unilateral military action is not acceptable."