The Thai navy on Saturday boarded the floating cabin of a fugitive U.S. bitcoin trader and his Thai girlfriend, both prominent members of the "seasteading" movement who possibly face the death sentence for setting up their offshore home.

Axar.az reports citing foreign media that Thai authorities have revoked the visa of American citizen Chad Elwartowski and have charged him and his partner, Supranee Thepdet, with violating Thai sovereignty by raising a small cabin on top of a weighted spar 14 nautical miles off the west-coast of Thai island of Phuket.

The cabin has been promoted as "the world's first seastead" by the group Ocean Builders, part of a movement in tech and libertarian circles to build floating communities beyond the bounds of nations as a way to explore alternative societies and governments.

"I was free for a moment. Probably the freest person in the world," Elwartowski posted on his Facebook on April 13, days before the Thai navy raided his floating home.

Elwartowski, 46, and Supranee, whose Facebook page describes her as a "Bitcoin expert, Trader, Chef, seastead Pioneer", apparently fled after a surveillance plane flew over the cabin the previous day.

The Royal Thai Navy task force had planned on Saturday to seize the structure and tow it back to shore for use as evidence, but by the afternoon it was still studying how to move it without destroying it, the navy said.

In a video posted last month detailing the raising of the floating home, Elwartowski said 20 more similar houses would be up for sale to form a community.

Elwartowski and Ocean Builders say the spar was in international waters and beyond Thailand's jurisdiction. Thai authorities say the structure is in its 200-mile exclusive economic zone and therefore a violation of its sovereignty.

A Thai navy task force was sent out on Saturday to tow in the structure which will be handed over to Phuket's police to be kept as an exhibit for the legal action, the navy said in an official statement.