Jakarta – Greenpeace is sending its flagship, the "Rainbow Warrior," on a campaign to stop illegal logging in Indonesia, the environmental pressure group said on Wednesday.

Steve Campbell, a campaigner for the group, said the ship, which arrived in Jakarta Tuesday, was on an Asia-Pacific environmental campaign and would sail for unspecified waters in Indonesia Saturday. But Campbell declined to give details of the campaign or how long it would last. "Greenpeace never would say whether or not we would take direct action. That would spoil it, really," Campbell told a news a conference at Jakarta's main port of Tanjung Priok where the ship docked.

"We do of course reserve the right to take direct action if we feel that is an important thing to do." In the past the "Rainbow Warrior" has been known for such tactics as attempting to block vessels carrying merchandise Greenpeace deemed to have been improperly processed environmentally.

Local environmental group Walhi said it would join in the Greenpeace effort against illegal logging in Indonesia.

"Walhi ...will work with Greenpeace to communicate to the world the dire state of Indonesian forests and the need for world support to save what's left of them," it said in a statement.

Most analysts rank deforestation as the most serious environmental threat facing Indonesia, home to the world's third largest tropical forests after Brazil and the Congo.

Local and international activists estimate the extent of Indonesia's tropical forest at roughly 100 million hectares.

Indonesia began to exploit its forests in earnest in the early 1970s, with the development of wood-processing industries.

Today it is a significant producer of tropical hardwood logs and sawn wood, plywood and other boards, and pulp for paper.