Thirteen Vietnamese nationals are being detained in Cairns for illegally fishing in Australian waters for sea cucumbers.

The Department of Immigration and Border Protection released a statement on Wednesday stating that more than three tonnes of sea cucumbers, considered a delicacy in Southeast Asia, were found on the vessel northeast of Rockhampton.

The Vietnamese crew were seen dumping some of their catch overboard, as Australian border agents approached the boat inside a conservation zone.

The crew is detained in Cairns while the Australian Fisheries Management Authority considers whether to lay charges.

– with AP