AMHERST, Mass. (AP) – One out of every three University of Massachusetts professors who took early retirement this summer is back working on the Amherst campus on a part-time basis just so the university has enough teachers to cover classes.

And one of every five other campus employees who took advantage of the retirement program aimed at easing the state’s money troubles was also rehired to keep computer and other operations going, officials said.

“It’s a stop gap,” said Leon Osterweil, dean of the College of Natural Sciences and Mathematics, which lost 30 faculty members to early retirement and rehired eight part-time.

The college replaced 12 retiring professors with new full-time faculty members and made “a huge number of temporary appointments,” both full and part-time to cover other classes, Osterweil said Monday.

Joyce Hatch, interim vice chancellor for administration and finance, said the early retirements helped cover a $10.2 million cut in the state appropriation of $223 million for the Amherst campus, but she could not be specific about savings.

“It’s complicated,” she said, pointing out that pensions come out of the state’s general fund and not the university’s operating budget and individual campus departments make staffing decisions out of their own operating budget.

However, Chancellor John Lombardi has said he plans to spend between $3 million and $4 million to replace the open faculty positions and another $2 million to fill support staff positions.

“We don’t have the kind of money to put them all back,” Lombardi told the Faculty Senate at a recent meeting. “But chunk by chunk we hope within three years to be back at full strength.”

Currently 35 of the 109 faculty members who took early retirement are back teaching at least one class, most at a rate based on their prior salary, officials said.

Under state pension laws, their hours are limited and their total public pension and post-retirement pay cannot exceed their salary before retirement.

Retired English professor John Nelson, who had taught at the university since 1967 and founded its technical writing program, told the Union-News of Springfield that he came back to teach the core course “so the program doesn’t die.”

“The university stands in what could be a much more dangerous situation than in the 1980s,” said retired math professor Edward Connors, warning that if the budget crisis continues, the university could find itself struggling to hold onto the young replacements for the retirees.

Connors, who is back teaching two courses after 14 members of the math department took early retirement, said in the last budget crisis the faculty’s strength was in people in their 40s and early 50s.

“They had already won their Nobel Prizes and they made the decision to stay and tough it out,” he said. “This time around the strength is in younger faculty and they are at a point in their careers when a move makes more sense.”

Ronald Story, president of the faculty union, is concerned that with heavier workloads younger faculty will get fed up and leave while more of the older faculty will get fed up and retire.