An Illegal fishing boat which had been operating in the Southern Ocean has been located and boarded by Australian Maritime officials.

The Kunlun had been illegally taking Patagonian toothfish from Antarctic waters and is wanted by Interpol.

The New Zealand Navy first found the vessel during a patrol of the ocean six weeks ago.

Then the Sea Shepherd Conservation group chased the ship for a week after finding it in Australia's Exclusive Economic Zone near Antarctica.

Australian Customs officials found and intercepted the ship near the Cocos Islands yesterday.

The Parliamentary Secretary to the Minister for Agriculture, Senator Richard Colbeck, said the vessel had been monitored for some time.

"They claimed to be flagged to Equatorial Guinea," he said.

"Equatorial Guinea told us they weren't flagged and under international law we can board a vessel on the high seas so that's what we've done."

The Kunlun is on the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) international blacklist of Illegal, Unregulated and Unreported (IUU) vessels.

The New Zealand government said the Kunlun and two other boats had been illegally fishing in the southern ocean for months.

New Zealand's foreign minister, Murray McCully, said he was pleased officials had intercepted the Kunlun.

"We are of course delighted to see that the Australian vessels have been able to gain access and add to the evidence," he said.

"We want to put these people out of business and anything that's going to contribute to that process is very welcome."

The Sea Shepherd Conservation Society has been patrolling the Southern Ocean this summer, looking for illegal fishing boats.

The group found the Kunlun near Australia's Mawson station in Antarctica three weeks ago.

Sea Shepherd captain Peter Hammarstedt said he wanted to see the boat impounded.

"It is a poaching vessel that was originally intercepted by the New Zealand Navy," he said.

"It was subsequently shut down from fishing by Sea Shepherd and we certainly applaud the actions of the Australian Government in finally taking action against illegal fishing in the southern ocean and boarding the Kunlun."

He said he suspected the vessel was en route from the Antarctic to South East Asia to offload its illegal catch.

Senator Colebeck said it would be illegal for Australian officials to arrest the boat's crew because it was on the high seas.

But Mr Hammarstedt said the ship's crew needed to face justice.

"Australia has every right to arrest this poaching vessel and we now expect to see it brought to the nearest Australian port to see justice done," he said.

The Kunlun is now heading north and Australia will be watching where it goes.

The Kunlun is one of six ships which is believed to engage in IUU fishing for Patagonian toothfish in the southern ocean.