Jakarta – A tanker loaded with more than 30,000 tons of palm oil forced its way out of an Indonesian port after a nine-hour stand off with a Greenpeace ship, activists said Saturday.

"The Westama pushed us away and forced their way out," Greenpeace's Sue Connor said. "They tried to leave at midnight after they finished loading. We tried to hold them off as long as possible."

Police had boarded the Greenpeace ship, the Rainbow Warrior, several times on Friday in Riau province's Dumai port.

Greenpeace is calling for the Indonesian government to implement a moratorium on deforestation and peatland destruction.

Palm oil plantations are rapidly expanding in Indonesia as global demand explodes – because it is seen as a green alternative to fossil fuels. It is also used in a range of consumer products such as cosmetics and biscuits. The Rainbow Warrior is in Indonesia ahead of a global climate change conference taking place in Bali next month.