TOKYO - A Japanese whaling ship with a New Zealand anti-whaling activist aboard on Friday sailed into Tokyo port where he was expected to face arrest for trespassing on the vessel, an AFP reporter saw.

Scores of police and TV camera crews on the pier awaited the arrival of the harpoon ship Shonan Maru II, while nationalist protesters flew Rising Sun flags and signs with abusive message about the "eco-terrorist."

New Zealander Peter Bethune is a member of the militant Sea Shepherd Conservation Society and was the captain of a high-tech powerboat that was sliced in two in a collision with the Shonan Maru II in January.

He climbed aboard the Japanese ship before dawn on February 15 from a jet ski with the stated intent of making a citizen's arrest of captain Hiroyuki Komiya for what he said was the attempted murder of his six crew.

Instead he was kept aboard the ship and is now expected to face arrest on suspicion of trespassing on a vessel. If convicted he faces up to three years in prison or a maximum fine of 100,000 yen (S$1,542).