Washington ? In a major setback to U.S. efforts to attract military help in Iraq, a Turkish official said Tuesday his country wouldn’t send peacekeeping troops without a significant change in the situation there. That makes it virtually certain the United States will have to send thousands more U.S. reservists early next year.

No additional countries have contributed forces in Iraq since the United Nations Security Council approved a new resolution last month. Bush administration officials had hoped the U.N. action would persuade reluctant allies to send more forces.

Turkey had been the best hope. But Turkey’s ambassador to the United States, Osman Faruk Logoglu, said his country would not send troops without an explicit invitation from the U.S.-appointed Iraqi Governing Council — some of whose members have vigorously opposed the idea.

The ambassador said it was up to the Americans to press the Iraqi council to make the invitation — a move he said the United States appeared unwilling to make.

“We felt that the Coalition Provisional Authority and also officials here in Washington could have probably persuaded the Iraqi Governing Council earlier on this issue,” Logoglu said.

A spokesman for the American-led authority in Iraq, Dan Senor, did not return a telephone message. State Department deputy spokesman Adam Ereli said the United States still believed Turkish troops would make a valuable contribution and that U.S. officials continued talks on the issue.

Defense Secretary Donald H. Rumsfeld has said more international forces would help ease the burden on the 132,000 American troops in Iraq. There now are about 23,000 other troops from more than 30 countries.

Pentagon officials say an infusion of thousands more international troops could prompt a reduction in the number of U.S. forces — although Rumsfeld said last month that any Turkish troops probably would not be in place soon enough to affect the Pentagon’s current troop rotation plans.

Under those plans, about 15,000 Army National Guard troops have been mobilized for possible service in Iraq beginning early next year, to replace weary active-duty troops who have been there nearly a year.

The newly mobilized troops are members of National Guard brigades from Arkansas, North Carolina and Washington state who are intended to combine with fresh active-duty troops.

In addition, the Pentagon might need to call up even more reservists in support units if Turkey or other countries don’t end up sending troops, Joint Chiefs of Staff Chairman Gen. Richard Myers said recently.

U.S. officials have ruled out the idea of increasing overall U.S. troop numbers in Iraq, instead saying they will speed up the process of getting trained Iraqi security forces into the streets to deal with an increasingly sophisticated and deadly insurgency.

They also have ruled out the idea of recalling Iraq’s previous army, as some Iraqi officials want