Turkey asked the United States to nearly double its multibillion dollar aid package as a condition for allowing U.S. troops on its soil in a war against neighboring Iraq, diplomats said Tuesday.

The Turkish parliament had been expected to vote Tuesday on whether to allow tens of thousands of U.S. combat troops in Turkey, which would be necessary for a northern front in any war against Iraq.

Instead, officials gave U.S. Ambassador Robert Pearson a new proposal late Monday for a beefed-up economic aid package that would provide compensation for any losses in an Iraq war.

Top politician Recep Tayyip Erdogan said authorization for U.S. combat troops to be deployed in Turkey depended on Washington meeting Turkish demands.

"The other side must meet our demands, and if they do, we shall see. After this is finalized, the authorization will come to parliament," Erdogan was quoted as saying by the Anatolia news agency.

The delay could upset U.S. war plans as ships carrying the tanks and armored vehicles that would be used in a thrust from Turkey into Iraq are already reportedly on the way to Turkey.

Washington says opening a northern front would shorten the war, making it less deadly.

A Western diplomat, speaking on condition of anonymity, said that although the United States had made its final offer to Turkey, Washington was reviewing the latest Turkish proposal. A response was expected later Tuesday or Wednesday.

The diplomat said Turkey had to make a decision on U.S. troops this week — the sooner the better — or risk being left out of any future planning of an Iraq war. Analysts warned that Turkish-U.S. relations also were at risk.

Newspapers reported that a vote could take place Thursday. Turkish officials refused to give a date.

Turkish and U.S. officials have been in intense negotiations for weeks on the conditions of the U.S. deployment.

Diplomats say a particular sticking point is an economic aid package to cushion NATO member Turkey from losses incurred in the war. Turkey is barely emerging from a deep economic crisis, which saw some 2 million people lose their jobs.

According to the proposal put forward by Turkish officials late Monday, Turkey is demanding $10 billion in grants and up to $20 billion in long-term loans, diplomats said.

Turks and Americans had been negotiating on the basis of $4 billion to $6 billion in grants and $10 billion to $15 billion in loans, according to news reports and diplomats. The grants reportedly would be split between cash and military debt write-offs.

Turkey's economy is heavily dependent on loans of the International Monetary Fund and U.S. support is seen as key for Ankara to secure the loans.

Erdogan, who is leader of the governing Justice and Development Party, warned that Turkey could not be forced into backing a U.S.-led war because of its economic difficulties.

"Nobody should expect a decision or an attitude dictated by Turkey's temporary problems and troubles," he said.

Erdogan urged the United States to take into account Turkey's importance as a strategic ally.

Erdogan appeared nonetheless to advise his party members to vote in favor of allowing the U.S. deployment.

"You will either remain outside the process, remain an onlooker to history and ... put up with the outcome, or you will play an active role in shaping history," Erdogan said.

Turkey wants to send tens of thousands of troops into northern Iraq to prevent the creation of a Kurdish state in northern Iraq, which its fears would boost aspirations among Turkey's 12 million Kurds.