COLUMBIA — Some state agencies aren't complying with requests by Gov. Mark Sanford and Gov.-elect Nikki Haley to freeze hiring, promotions and raises because officials say they can't.

At the Department of Mental Health, for example, the agency says it has had trouble recruiting key medical personnel and cannot leave the jobs open and sometimes has to increase pay to keep the agency competitive.

"It's not as simple as putting a freeze on all hiring or on all salary increases," Director John Magill said.

"Turnover among clinical staff is ongoing. The department's mental health centers, hospitals and nursing care facilities require an adequate number of nurses and other medical professionals to operate. If the department doesn't recruit and retain qualified clinical staff, the agency must either contract for them at significantly higher market rates, or reduce its clinical services even more."

Sanford told directors at his cabinet agencies to freeze hirings, promotions and raises in advance of what are expected to be further budget cuts next year to deal with a projected $700 million shortfall in the state's General Fund, the portion of the budget that uses state income and sales tax revenues.

Over the past three years, that portion of the budget has shrunk by about $2 billion because of declining tax revenues and an ailing economy. Haley has urged the rest of state government to voluntarily comply with Sanford's order to cabinet agencies.

"It's understood that we're in one of the toughest budget challenges this state has faced in half a century and obviously state government is going to have to tighten its belt," said Ben Fox, Sanford's spokesman. "I think frankly other agencies that are not in the cabinet that are following the lead of cabinet agencies would probably be taking the wise course here."

Some of those agencies, however, say they can't adopt blanket freezes.

"It's case by case," said Jim Foster, a spokesman for the Department of Education, where about half of the 880 employees are bus mechanics. "If we lose a bus mechanic, that's not a position we can freeze. We don't have enough bus mechanics as it is."

University of South Carolina President Harris Pastides said staffers there continue to be promoted.

He said USC has a hiring freeze with exceptions "but they have to be defended vigorously."

He said there haven't been salary increases in several years.

At the State Budget and Control Board, the state's administrative agency, spokesman Michael Sponhour said some jobs continue to be filled if they are in critical positions.

"We have reduced our work force significantly during the last several years and in the spirit of Gov.-Elect Haley's request, it is our policy to suspend requests for pay increases and to hold promotions in abeyance until further notice," he said.

The total state government workforce has declined from 63,115 in 2009 to 60,734 as of last week, Sponhour said.

That doesn't include agencies such as the State Lottery, Ports Authority and legislative employees, which aren't included in the state personnel database.

The Department of Health and Environmental Control, one of the state's largest agencies with a workforce of more than 4,100, cannot freeze all hiring because federally funded programs have certain requirements for staffing, spokesman Adam Myrick said.

"Currently, hiring is only for essential positions and salary increases are given only in special situations," he said.

"It's also important to note, we can't do an all-out, across-the-board freeze because of statutory requirements and requirements of other funding sources [i.e., fees, federal program dollars, and grants which carry staffing requirements with them]."

At the Mental Health Department, officials say the agency has lost $82 million, or 37 percent, in recurring funding since 2008.

The agency's pay levels for nurses and entry mental health counselors are up to 20 percent less than in the private market, they say.

"In order to attract or retain the professional staff required to provide mental health services, it is often necessary to increase salaries, sometimes by a significant amount," Magill said.

"Yet due to the budget crisis, the department has also had to cut services and ask many of its employees to take on additional duties with no pay raise, or even absorb an involuntary furlough."