Police and local rangers on Elcho Island this morning responded to reports of a suspicious Viking ship moving slowly around the island.

Approaching the 15 metre long wooden vessel with extreme caution, the rangers said they prepared themselves for anything.

"With swords drawn, it was established the Viking vessel was a replica, crewed by six Russians who had sailed from Europe," Watch Commander Gary Smith said.

The ship has travelled from Europe through Africa, Thailand and now the Northern Territory on its way to Sydney where it will be given to a Museum.

"We've done all the relevant customs and immigration checks and it was all legit so the Russians went on their merry way," Mr Smith said, adding that they travelled at a top speed of eight knots.

Ranger Damien Clayton said the initial reports suggested the boat could be carrying asylum seekers.

"We had reports a wooden boat was anchored out just offshore of the community on the western side (of Elcho Island) that looked a bit suspicious," he said.

"It slowly moved around to the eastern side then we got more reports it could possibly be asylum seekers or illegal immigrants.

"We contacted police then we made a move in the early morning...we are very apprehensive on moving in on things like that - you never know what's going to happen."

Mr Clayton admitted the boat did look "pretty amazing" on a closer inspection.

The Russian crew are reported to have been very cooperative with their limited English, showing their passports, and obliging for a few photographs.