An internal State Department study has concluded that up to 17 percent of U.S. diplomats at dangerous posts abroad may suffer from post-traumatic stress disorder, although some fear the figure is far higher in Iraq and Afghanistan.

The findings are contained in a cable expected to be sent to U.S. embassies on Tuesday despite concerns they do not reflect the full scope of mental health problems among diplomats who serve in Baghdad and Kabul, the department's two most dangerous posts, according to officials familiar with the matter.

The numbers were drawn from a survey of about 2,600 diplomats who have worked over the past five years at the department's 21 so-called "unaccompanied" embassies and consulates, where either spouses or other dependents are not allowed for security reasons, they said.

The officials spoke on condition of anonymity because the results are not yet public and the cable has not yet been sent.

The survey was begun in the spring to evaluate mental strains on the U.S. diplomatic corps as its members are asked to serve in growing numbers at increasingly dangerous places, particularly Iraq and Afghanistan, where they are at risk from insurgent attacks.

The cable, a draft copy of which was seen by The Associated Press, says that post-traumatic stress disorder, or PTSD, "is probably present in 2 percent of respondents. Another 15 percent of respondents possibly have this disorder but would require a more thorough examination to make a definitive diagnosis."

While not disputing those figures, the union that represents U.S. diplomats — the American Foreign Service Association, or AFSA — says they could be misleading because they include all 21 unaccompanied posts in the State Departments network and do not break the numbers out by specific mission.

In addition to Iraq and Afghanistan, those posts include four missions in Pakistan, three in Saudi Arabia and one each in Burundi, Bosnia, the Central African Republic, Haiti, Ivory Coast, Lebanon, Liberia, Serbia (Kosovo) and Yemen.

One AFSA representative said that lumping results from posts like those in Haiti, Congo or Liberia would likely skew the figures from far more dangerous places, notably Baghdad, where U.S. diplomats routinely cope with insurgent shelling in the fortified "Green Zone" where the embassy and their quarters are housed.

The representative said the union had won a pledge from the department's medical unit to break out the figures by location. That breakdown, however, will not be ready for Tuesday's expected release of the survey, the State Department said.

AFSA officials have said their information suggests that as many as 40 percent of diplomats, especially those returning from Iraq and Afghanistan, struggle to readjust to civilian life and suffer from stress disorders, including thoughts of suicide. They note that the civilian foreign service, unlike the military, lacks key support systems to help those in need.

The State Department has questioned the AFSA estimate but has pledged to provide the medical and psychological support necessary to deal with what it acknowledges is a growing problem.

The report comes as Secretary of State Condoleezza Rice has made embassy staffing in Iraq a priority, offering incentives for diplomats to serve there, including substantial danger pay, limited tours of duty and choice of next assignment.

Still, the department has said it may have to compel some foreign service officers to work there in the coming months and years because of the limited pool of qualified staff.