A group of 18 Sri Lankan men detained on Christmas Island chose to return home rather than be sent to Nauru for processing, in a move the federal government is claiming as a major victory for its tough new asylum seeker laws.

The men - most of whom arrived after the government announced the new policy - were sent back to Colombo on a charter flight this morning.

“Both the Nauru transfers and this group of adult Sri Lankan men choosing to return home provide further evidence that the people smugglers are selling lies and misleading asylum seekers about the situation they will face if they reach Australia by boat," the Immigration Minister, Chris Bowen, said.

Two of the 18 men arrived in Australia before the government announced changes to the processing system but they also chose to return to Sri Lanka voluntarily. The other 16 arrived after the changes were announced in August.

Mr Bowen said the men had realised they had been lied to by people smugglers who promised them visas on arrival in Australia.