BOSTON – The federal maritime agency has ordered one quarter of crew members on liquefied natural gas tankers docking at two proposed offshore terminals in Massachusetts Bay to be American citizens, according to a report published Saturday.

U.S. Maritime Administrator Sean T. Connaughton said the rule will ensure that Americans have access to lucrative tanker jobs. The rule will also enhance safety because Americans will be aboard the ships as they unload the highly flammable liquid, the Boston Globe reported.

Connaughton said the policy would affect two terminals that are being planned off of Gloucester and Fall River, but would not affect the existing facility in Everett.

Gov. Deval Patrick applauded the policy, saying it would benefit the state economically and enhance security, according to the report.

The two facilities would be New England’s first offshore LNG terminals. Liquefied natural gas is warmed to make natural gas used in heating, cooking and electricity generation.

Both facilities would use underwater pipelines to connect to New England’s distribution network.

Both projects already received state approval.

But another proposed terminal, in southeastern Massachusetts, has hit a snag after the U.S. Coast Guard cited navigational safety, security and environmental concerns in a recent 16-page “preliminary assessment” letter to developers.

A spokesman for Weaver’s Cove Energy, however, said the developers plan to press ahead despite hurdles from the Coast Guard that opponents say could doom the project.

The proposal by Weaver’s Cove and Hess LNG for a terminal on the banks of the Taunton River in Fall River has won approval from the Federal Energy Regulatory Commission.