Pro-asylum seeker banner in Sydney Harbour

Protesters have taken to the water to appeal to the federal government to let asylum seekers facing deportation to Nauru to remain in Australia.

Protesters in boats on Sydney Harbour have unfurled a banner in support of asylum seekers facing deportation to Nauru.

The group, in two inflatables, held up a "#letthemstay" banner in protest at a High Court decision that cleared the way for 267 asylum seekers to be returned to Nauru following a failed challenge to offshore processing.

Amnesty International, Greenpeace Australia, GetUp and ActionAid were behind Sunday's action.