WASHINGTON - A shortage of diplomats will force the State Department to leave open 10 percent of its vacant positions around the world, with the exception of key posts such as in Iraq and Afghanistan.

At least 150 jobs in Washington and overseas missions scheduled to be filled next year will have to be deferred as the department struggles with "severe staffing shortfalls," Foreign Service Director General Harry Thomas said in a worldwide cable yesterday. The move comes even as the Bush administration is seeking to ramp up its international outreach.

"The department's staffing has not kept pace with current needs," he said in the unclassified cable.

"Bureaus have been tasked with restrictions on 10 percent of midlevel generalist jobs in the current assignments cycle," he said.

AP obtained a copy of the cable shortly after it was distributed through the State Department's internal messaging system.

Although keeping vacant positions open is not unprecedented - some embassies operate at only 70 percent of their full-strength staffing levels - the move follows a highly publicized dispute over the possibility of forced service in Iraq and comes as the department considers "directed assignments" to other hardship posts.

"Critical new requirements (e.g. Iraq, Afghanistan, Libya) and a growing number of one-year jobs have translated into serious deficits" in qualified personnel at various seniority levels and specialties, Thomas wrote, noting that training requirements for numerous posts often cause delays in assignments.

Much of the problem, he said, lies with Congress, which has not authorized any significant increase in the size of the foreign service since 2004.

Thomas said he had ordered each bureau to determine by Monday which 10 percent of its positions to leave vacant.