Federal regulators facing a key deadline have "stopped the clock" in evaluating a controversial plan to build a natural gas transfer station 19 miles off Jones Beach.

In a March 17 letter posted online Tuesday, the Coast Guard and the federal Maritime Administration noted it had only 21 more calendar days under the law to hold the last public hearings on Port Ambrose, proposed by Liberty Natural Gas.

The agencies cited four reasons for why they could not meet that timeline on the plan, opposed by many public officials, shoreline residents and environmentalists.

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First, more than 10,000 public comments have come in, according to the letter, and time is needed to respond and review to each one.

Also, EPA must still review the project, authorities said, and Liberty has until Monday to submit financial data.

Last, the Army Corps of Engineers began this month requiring pipelines to be buried 15 feet deep instead of 7 feet, a new rule that will have to be analyzed for the final environmental impact report, the letter said.

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Liberty's chief executive, Roger Whelan, said stopping the clock is a normal part of the federal license application.

"We support the Coast Guard's efforts to conduct an extensive and thorough federal review and are confident the results will show the Port Ambrose project will have minimal impact on the environment," he said in a statement. He said the proposal would bring several benefits, including lowering energy costs during peak winter demand.

In the Port Ambrose plan, two buoys that load gas would rise from the ocean floor to hook up to the tanker.

The vessels would deliver liquefied natural gas from the Caribbean and turn it into a gaseous state to pump into one of two, 2-mile pipelines that connect to a 22-mile main pipeline. These pipes would have to be built and buried. The main would link up to an existing natural gas pipeline system that serves Long Island and New York City.

It was the second suspension of the timeline since Liberty's proposal was officially published by federal authorities in June 2013.

Although federal authorities have not said how long they'll stop the clock, critics of the plan welcomed the break. They are pressuring Gov. Andrew M. Cuomo or his New Jersey counterpart, Chris Christie, to kill a project they see as a step back from renewable energy and an explosive target for terrorists. Under federal law, one veto from a governor kills the plan.

Seth Gladstone, spokesman for the Brooklyn-based Food and Water Watch, recently started organizing what he hopes is the same kind of pressure that helped defeat fracking in the state last year.

"This is a good thing for this growing movement to make sure Port Ambrose never happens," he said. "This gives us more time to organize, more time to educate."