WASHINGTON – Saying they tried to balance New England’s energy needs with public safety concerns, federal regulators Thursday approved plans for a liquefied natural gas terminal in Fall River, Mass., but rejected a proposed expansion of an LNG facility in Providence, R.I.

It was the Federal Energy Regulatory Commission’s first rejection of a new LNG facility; seven others have been approved since 2003.

The commission approved the $250 million Weaver’s Cove project for Fall River by a 3-1 vote. Commissioners said the project met safety standards, though residents and government officials have protested it would put the community at risk.

Commissioner Suedeen Kelly, the lone dissenter, said the project would damage the environment and aquatic life in the river, and that tanker traffic along the narrow Taunton River would raise safety concerns and disrupt the community.

Fall River mayor Edward Lambert and Rep. James McGovern, D-Mass., who watched the vote, vowed to do whatever is necessary to defeat the proposal, including suing in federal court. Massachusetts Attorney General Thomas Reilly said officials are asking FERC to reconsider its decision.

“We’ll kill this project with a thousand paper cuts,” said Lambert. “We’ll use every avenue – legal, political, public relations and regulatory.”

Commission chairman Pat Wood said he knew the vote would not be popular, but said the terminal would help meet New England’s serious energy needs.

“We are looking at the long-range economic health of the oldest region in our country,” he said. Wood added that the commission needs to better educate the public on the benefits of LNG and FERC’s role in the approval process.

Members of Massachusetts’ congressional delegation, along with lawmakers from Rhode Island, all said they plan to fight the Weaver’s Cove decision, saying the terminal is an attractive target for terrorists and will put residents in both states at risk.

Gordon Shearer, chief executive officer of Weaver’s Cove Energy, said the company is prepared for a legal battle.

“We don’t expect this to come quickly, but we’re well down the road,” he said. “We would not have gone as far as we have, if we were not comfortable that we would be able to comply with the permits.”

The commission voted 4-0 to reject the KeySpan LNG proposal in Providence, saying the project didn’t meet safety standards. Commissioners said that converting the existing LNG storage tank on the Providence waterfront into an import terminal would require KeySpan to bring the facility up to current safety standards.

“New England does need additional LNG import capacity,” said FERC commissioner Joseph Kelliher. “This [vote] demonstrates that the commission does apply high safety standards.”

The company has said it would cost more than $35 million and would force officials to take the tank out of service for two to three seasons.

KeySpan executive vice president David Manning said the company is disappointed by the vote, and will consider its options after reading the full FERC decision.

A significant issue, he said, will be FERC’s conclusion that the project is a new terminal that must be brought up to current code, rather than an existing facility that meets applicable standards and would not need costly safety upgrades.