"We arrested nine men for alleged illegal entry," said an official at the coastguard in Okinawa. "This brings the total number of people arrested to 14."

The new arrests came after police arrested five men on the archipelago the activists know as Diaoyu but which Japan calls Senkaku.

The activists, who belong to the Action Committee for Defending the Diaoyu Islands, had said the move was aimed at countering a plan by a group of Japanese lawmakers to visit the disputed islands this weekend.

A Japanese coastguard spokesman confirmed the nine new arrests on suspicion of illegally entering Japan, adding: "We have now taken a total of 14 people into custody and will carry out full investigation."

NHK said authorities were sending the arrested to the Okinawa main island for investigation.