The United States and the main Iraqi Kurdish groups failed tonight to persuade Turkey to keep its troops out of northern Iraq if a war begins, although the Turks said they would participate in a committee that would try to minimize the risk of clashes between their forces.

[The Turkish prime minister, Recep Tayyip Erdogan, responding to urgent phone calls from Secretary of State Colin L. Powell, agreed to ask parliament to immediately authorize the U.S. use of Turkish airspace, a cabinet spokesman said early Wednesday. The spokesman said the measure would be presented to parliament later in the day.

[The 2:30 a.m. announcement followed a lengthy and apparently contentious meeting of Erdogan's cabinet. A statement issued about midnight said discussions about the overflight rights were continuing but that Erdogan planned to present a motion to let U.S. troops use Turkish territory to attack Iraq, a proposal that parliament had previously rejected. In its latest announcement, the cabinet said any consideration of a U.S. ground deployment in Turkey would now be delayed indefinitely.]

In recent days, U.S. officials have pressed especially hard for the overflight rights, which are important to Pentagon plans to hit Iraqi targets and move troops to northern Iraq. Permission to deploy U.S. troops on Turkish soil is considered less urgent, because the U.S. military appears to have concluded it cannot deploy ground forces to Turkey in time for the start of the war.

U.S. officials have declined to say whether Turkey is moving too late to receive the $6 billion aid package that Washington had offered and then said it was withdrawing.

U.S. officials also declined to say whether the United States would revive a previous agreement to let Turkish troops take up positions about 121/2 miles over the border in northern Iraq if the U.S. deployment was approved. Frustrated by weeks of delays, the Bush administration abandoned the deal last week and has been urging Turkey to stay out of Iraq.

Any Turkish measure allowing a U.S. deployment would almost certainly authorize Turkish troops to enter northern Iraq as well. But in a three-hour meeting today, U.S. and Kurdish officials warned that a unilateral Turkish incursion could lead to fighting between Turkish and Kurdish troops and could prompt other neighboring countries, such as Iran and Syria, to send forces into Iraq, according to officials who participated in the talks.

But Turkey was unmoved, and continued to reserve its right to enter northern Iraq to protect its national security. The officials said Turkish diplomats argued that the Kurds had nothing to fear because the Turkish forces would be entering Iraq just to stop a refugee crisis and to prevent attacks on Turkey from Iraqi territory.

In the end, the parties agreed only on a vague U.S. plan to establish a coordinating group that would try to reduce tensions and determine whether Turkey's concerns could be addressed without its troops entering Iraq. "We are thinking of a mechanism where Iraqis, Turks and Americans will remain in touch to deal with issues as they arise, and that's where we left it," said Zalmay Khalilzad, the Bush administration's special envoy to the Iraqi opposition.

Khalilzad reported progress in other areas, saying the Turks and Iraqi Kurds agreed that U.S. forces would take control of the oil-rich northern Iraqi cities of Kirkuk and Mosul and set up a commission to evaluate claims of refugees who want to return there. He said the two sides agreed to discourage large population flows into the area and would refrain from inciting civil discord.

But the uncertainty about Turkey's military plans, even as a war appeared imminent, overshadowed the other results. U.S. officials have warned that a Turkish incursion could provoke Iraqi Kurdish militias suspicious of Turkey's motives and result in a "war within a war."

Turkish Prime Minister Recep Tayyip Erdogan, right, consults with Foreign Minister Abdullah Gul at the parliament.