Media reports indicate up to 50 asylum seekers were on board the HMAS Choules on Friday and due to arrive in the port of Vung Tau

This article is more than 5 years old

This article is more than 5 years old

The Australian government has reportedly used a costly navy vessel to return a number of asylum seekers to Vietnam.

Up to 50 people were on board the Navy supply ship HMAS Choules, the West Australian reported on Friday.

The asylum seekers’ vessel was reportedly intercepted in early April.

HMAS Choules left Darwin on 5 April but no publicly available data shows its record beyond there.

It’s not clear if the asylum seekers were intercepted and then brought to the mainland, or held on the vessel, but local sources say no large group of Vietnamese asylum seekers has been moved in or out of Darwin in recent weeks.

A previous interception involved a controversial fast-track process to screen 38 Sri Lankan asylum seekers while still at sea, before returning 37 of them to Sri Lanka.

In January the high court found found the detention of 157 Tamil asylum seekers on board the Ocean Protector at sea for more than a month last year was lawful.

HMAS Choules was due to arrive in Vung Tau, south of Ho Chi Minh city, within the next day, Fairfax Media reported.

The ship is large enough to carry up to 700 personnel, and has a flight deck “which can accommodate two large helicopters and a docking well in the stern capable of operating a LCM-8 or two LCVP landing craft,” according to the navy. The West Australian reports it has a daily running cost of more than $201,000.

Defence, customs and the immigration department have been contacted for comment, but the Abbott government generally does not comment about “on-water matters”.

Guardian Australia has previously revealed the Australian government engaged a Vietnamese shipbuilding company in the construction of several Vietnamese fishing boat style vessels, to be used in towback operations instead of $46,000, single-use orange lifeboats.

The wooden vessels have been stored in dry dock in Darwin. Another similar-looking vessel built of alloy is kept in a nearby bay and has been taken out frequently in recent years, according to a local dock worker familiar with it.