A small fleet of brightly coloured Vietnamese fishing boats based in Darwin are believed to be replacing the orange lifeboats used by the Customs and Border Protection department to tow back asylum seeker boats that make it to Australian waters.

Fairfax Media understands that 10 red, blue and green wooden boats have been bought by the Customs department from Dragon Industries Asia as "tow back" boats in a multi-million dollar project.

Two of the Vietnamese fishing boats in a Darwin boat yard on Thursday. Credit:Glenn Campbell

Having succeeded in "stopping the boats", it appears the Abbott government has opted for a cheaper alternative to the orange lifeboats, which cost the government $7.5 million last year.

It is believed each orange lifeboat, which can only be used once, costs about $200,000.