BOSTON – A proposed liquefied natural gas terminal in southeastern Massachusetts hit another roadblock Monday when state environmental regulators halted their review of the plan.

The state Department of Environmental Protection says it will stop its review of permit applications by Weaver’s Cove Energy and Hess LNG, citing concerns about the project raised recently by the Coast Guard.

“This situation warrants MassDEP’s reassessment of its expenditure of limited permitting resources on the pending permit applications,” Arleen O’Donnell, acting commissioner, wrote Monday in a letter to Weaver’s Cove Energy.

The proposal for a terminal on the banks of the Taunton River in Fall River has won approval from the Federal Energy Regulatory Commission. But the Coast Guard cited navigational safety, security and environmental concerns in a May 9 “preliminary assessment.”

O’Donnell said if the Coast Guard eventually determines that the waterway is suitable, the state would resume its review. A final report from the Coast Guard is expected later this summer.

“While preliminary in nature, the substance and outcome of the Coast Guard’s May 9, 2007, determination represents a significant change in the overall status of the Weaver’s Cove project and casts serious doubt as to the feasibility of the project,” O’Donnell said.

Jim Grasso, a spokesman for Weaver’s Cove Energy, expressed confidence that the state’s decision won’t stop them.

“This is not an unusual action for an agency to take for a project like this,” he said. “We intend to get approval from the Coast Guard. The project is moving forward.”

Capt. Roy A. Nash, commander of the Coast Guard’s southeastern New England sector, wrote last month that the developers have yet to show that LNG tankers “can be safely navigated through this waterway on a consistent, repeatable basis.”

Reiterating a concern he raised in March 2006, Nash said 750-foot tankers would need to perform an “extraordinary navigational maneuver” to pass through the old and new Brightman Street bridges, which are about 1,100 feet apart and offset. The older, smaller bridge has a 98-foot navigational opening. The tankers are 85 feet wide.

Critics fear the LNG terminal could endanger residents in the densely populated area. They say almost 64,000 people live along the tanker route. A terrorist strike or accident could be devastating, they warn.

Weaver’s Cove Energy, however, argues the Northeast needs the facility to meet growing energy demands. Some energy analysts have predicted that by 2010 there won’t be enough natural gas supply to keep up with the region’s energy needs.

“We are facing brownouts and blackouts in three to five years if these projects are not built,” Grasso said of this and other proposed LNG facilities.