Nationals Senator Barnaby Joyce says the Federal Government should send a group of asylum seekers on board an Australian Customs ship back to Sri Lanka.

The 78 Sri Lankans have been on board the Oceanic Viking for three weeks and are refusing to get off because they do not want to be sent to an Indonesian detention centre.

The Federal Government has ruled out bringing the group to Christmas Island.

Senator Joyce told Channel Nine that Prime Minister Kevin Rudd should speak directly to the Sri Lankan President about the issue.

"If you want to show strength, if you want to be decisive - and he loves that description of himself as decisive - then send the Oceanic Viking to Colombo and you really will have made a strong statement," he said.

The Sri Lankan High Commissioner to Australia, Senaka Walgampaya, has told Channel Ten it is likely the group would be accepted.

"Sri Lanka has to be satisfied that these people are still Sri Lankan nationals, that they don't hold passports of any other country," he said.

"If they are in fact Sri Lankans, they would be taken back."

Mr Walgampaya says the people on board the Oceanic Viking are economic refugees.

"They would like to come here to Australia and they are making use of the post-conflict situation in Sri Lanka to make that excuse to seek asylum in Australia."

But the Federal Government has accused the Opposition of exacerbating the stand-off.

Frontbencher Peter Garrett has told Channel Ten the Opposition is just trying to fuel community fears.

"All that the Opposition have really done is seek to make political points, seek to exacerbate what is clearly a difficult situation, one that requires adept management by any government, and one that this Government's taking very seriously," he said.