PORTLAND – The suspension of 10 officials from the largest union at Bath Iron Works comes as the Machinists union and the Navy shipbuilder prepare for the first contract negotiations in four years.

But both union and shipyard representatives insist negotiations will begin on schedule next month with an eye toward reaching an agreement before the current contract expires at midnight on May 18.

Local S6 President Mike Keenan and some of the other suspended leaders were members of the negotiating committee, and it remains to be seen whether they’ll be reinstated before negotiations begin. The negotiating committee is due to participate in a union prep session in the first week of April.

The trustee overseeing the 3,500-member Local S6 for the time being already had been appointed to oversee negotiations, John Carr, spokesman for the Machinists union, said.

“Negotiations aren’t going to change,” Carr said. “These suspensions are just a small part of the negotiation committee. There are several people who sit on that negotiation committee and many of them weren’t suspended.”

The union was thrown into turmoil Monday when Keenan, the vice president, recording secretary, financial secretary and three other officers and three local trustees were escorted from the union hall and the union was placed under management of regional union officials.

The Machinists union is investigating a number of accusations including financial improprieties, misuse of computers, election irregularities, and a backlog of grievances. Among the accusations were complaints about pornography found on computers and a failure to account for union-labor merchandise that could exceed $100,000 in value.

Some allegations against Local S6 officials were serious enough to warrant a separate investigation by the U.S. Department of Labor, Carr said.

Keenan has issued a point-by-point rebuttal. “I’ve never seen anything like this,” Keenan said Thursday from his Bath home. “I’m so appalled. I’m so disappointed.”

A meeting to discuss the investigators’ findings is scheduled for April 14, but it’s possible some of the union leaders could be allowed to return before then if they’re exonerated.

The shakeup comes at a sensitive time. The shipyard and union will be negotiating a contract as the Navy contractor scrambles to fill a potential gap in work as the Arleigh Burke destroyer program wraps up and the next-generation DDG-1000 destroyer ramps up over the next couple of years.

James DeMartini, spokesman for the shipyard, said the company and the union have cooperated to make the shipyard more efficient to lower costs and obtain more work.

“We’re anxious to keep the momentum going,” he said. “We have every reason to believe we’ll continue to do what we need to do to get our respective jobs done here.”

Such investigations are relatively unusual, but when they do happen it’s common for the parent union to remove local officers during an investigation, said John Hanson, former director of the University of Maine Bureau of Labor and current executive director of the Maine State Building and Construction Trades Council.

“What they really want to do is to get everyone who’s closer than arm’s length, to get them away, get them out of there, so they can’t take away any documents or anything like that,” Hanson said.

Such investigations are always contentious. “A lot of people jump to conclusions, but that’s what the investigation is for, to see if there is any substance to the charges,” he said.