Armed Russian security forces are said to have broken down a barricaded door to arrest two Australian residents among 28 Greenpeace activists protesting against oil exploration in the Arctic.

Alexandra Harris, of Sydney, and Tasmanian Colin Russell, held out against the Russian boarders in the radio room of their campaign ship ''Arctic Sunrise'', the environmental organisation said.

''The last message we got from them was that 'they are trying to enter the radio room, and they are destroying the door','' said Greenpeace Australia spokeswoman, Julie Macken.

Ms Harris, 27, is a British national resident in Sydney who works as the group's social media ''whiz kid'', Ms Macken said. Mr Russell, 59, is a marine radio operator from Woodbridge in Tasmania who earlier this year campaigned aboard ''Rainbow Warrior'' on the Great Barrier Reef.