BATH – The suspended leader of Bath Iron Works’ largest union has urged members to reject a contract offer that holds the line on health care contributions, increases pension contributions and provides workers with pay hikes of 3.5 percent to 4 percent per year.

Local S6, which has been in disarray since top officers were suspended by the international Machinists union, will vote Sunday at the Augusta Civic Center on whether to approve the four-year contract.

The 3,800-member Local S6 was placed into receivership in March because of accusations including mismanagement of money and pornography on union computers.

Key Local S6 leaders including President Mike Keenan remain suspended from their union posts and did not take part in the negotiations. Vice President Troy Osgood resigned his post this week, describing the international union as “similar … to an authoritarian dictatorship.”

In a letter sent Friday to Local S6 members, Keenan called the contract a “sellout of major proportions,” the Portland Press Herald reported on its Web site.

Keenan wrote that in the past, Local S6 had rights under the contract to enforce its provisions, while the new language would give the same rights to the international union and its District Lodge 4.

He also noted that the proposed agreement has language allowing either party to reopen negotiations at any time before Jan. 15, 2012, if “economic, operational or competitive” conditions change.

Machinists spokesman John Carr said Friday he believes the contract negotiated with BIW is one of the best in the industry.

The proposal provides a pay increase of 3.5 percent in the first year, 3.8 percent in the second and third years and 4 percent in the final year, Carr said.

Also, health care remains the same with no increases in employee contributions, Carr added, though some deductibles and co-pays would increase under some plans. BIW also will increase its contributions to employee pensions, he said.

“If this is not an industry-leading agreement, then it’s tied for it,” Carr said. “It’s a healthy package and it should secure the future of our members through the life of the agreement.”

There was some confusion over the length of the contract. Some early reports indicated it was a traditional three-year deal, but Carr said it will be a four-year pact like the old contract, which expires at midnight Sunday, hours after the union members cast their tallies.