PORTLAND – The president of Guilford Transportation Industries reacted angrily to suggestions that Amtrak consider taking his rail line by eminent domain to get the long-awaited passenger service between Portland and Boston back on track.

“I’m the owner of that property you want to take,” David Fink said at a City Hall news conference called Thursday by passenger train activists dismayed by the latest delay in the start of the service.

Speaking loudly and sometimes angrily, Fink said Guilford is not standing in the way of passenger service. But he said he would not allow trains to travel more than 59 mph because the line’s new 115-pound rail is not engineered for higher speeds.

Backers of the passenger service want the trains to run at 79 mph. Wayne Davis of TrainRiders Northeast expressed doubt that the slower speed would attract enough riders to sustain the service.

The service, which had been tentatively scheduled to start this May, has been put on hold until several issues between Guilford and the Northern New England Passenger Rail Authority are resolved.

Fink showed up at the news conference with other Guilford officials and walked up to the podium after hearing someone remark about the use of eminent domain.

The rail authority wants Guilford to allow the rails to be tested to show that the lines can be maintained to meet industry standards, as stipulated in a 1999 ruling by the federal Surface Transportation Board.

But Fink said any test would be flawed because it can test only a section of rail at any moment and can not assure him that the entire 78-mile stretch owned by Guilford is safe all the time. He said the rails aren’t heavy enough and the granite beds aren’t deep enough to meet requirements for rail rigidity. He said there is no test available that will convince him otherwise.

“I’m the person who sets the standards on my railroad,” he said. “We are not going to jeopardize other people’s safety. That is all there is to it.”

Although Guilford owns the line, federal law gives Amtrak the right to operate over any railroad. It also has the power to take a rail line by eminent domain, but Amtrak and Northern New England Passenger Rail Authority officials have not talked about doing that.

State officials said Thursday they have yet to decide whether to start train service at 59 mph or wait until they can get a ruling from the Surface Transportation Board that would allow for greater speed. That ruling could take several months.