The Turkish president has said his country will allow US soldiers to be deployed on its territory only if the United Nations passes a second resolution authorising the use of force against Iraq.
Most Turkish people are opposed to war
Turkey, which borders Iraq, is a key US ally and its role would be critical in any US-led invasion of Iraq to disarm Saddam Hussein.
The Turkish Government postponed voting on the issue on Tuesday, and although parliament could sanction the deployment of US troops without a new UN resolution, President Ahmet Necdet Sezer has the power to veto its decision.
In order to have a situation deemed legitimate... we believe there should be a Security Council resolution other than Resolution 1441
The Iraqi Kurdish leader whose guerrilla forces control the area south of the border with Turkey has warned of major problems if Turkish forces cross into northern Iraq.
Massoud Barzani, who heads the Kurdish Democratic Party, said there was no reason for any such move and it would only complicate the situation.
It has been widely reported that Washington agreed to a Turkish request to put troops into a buffer-zone across the border as part of the price for allowing American and British troops to pass through Turkey, says BBC correspondent Jim Muir in northern Iraq.
But Mr Barzani told the BBC that the Kurds would not be bound by any such agreement.
Turkey had previously appeared to be holding out for a package of financial compensation before accepting US troop deployments.
Prime Minister Abdullah Gul had said parliament was unlikely to allow in tens of thousands of United States troops before the political, economic and military dimensions of the deployment had been agreed.
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Without US influence, there would be no rift amongst EU governments.
Turkey fears it could incur heavy costs in the event of war, including the cost of housing Iraqi refugees, and is seeking a multi-billion dollar aid package.
The president's announcement that a second resolution will also be necessary could slow down military preparations and hinder plans for a northern front in the war.
Mr Sezer said US troops could only be deployed in Turkey "in circumstances considered legitimate by international law.
"In order to have a situation deemed legitimate... we believe there should be a Security Council resolution other than Resolution 1441," he was quoted as saying by the Anatolia news agency.
We continue to work
with Turkey as a friend. But it is decision time
White House spokesman
Turkish public opinion is overwhelmingly opposed to any war with Iraq, but the government has said it could not afford to stay neutral in the event of a conflict.
"It... will be settled one way or another rather soon," White House spokesman Ari Fleischer said. "We continue to work
with Turkey as a friend. But it is decision time. We will find out what the ultimate outcome is."
The US is a key ally of Turkey, lobbying for Ankara to be accepted into the European Union and for international agencies to grant Turkey loans to recover from a deep economic crisis.
The US said on Tuesday it was "decision time" for Turkey to accept an aid package worth nearly $26bn.