Tony Abbott has conceded it is possible no Indonesian fishing boats will be bought by the Australian government under a scheme he has proposed to tackle people smuggling.

The opposition leader last week announced the coalition would buy fishing boats from Indonesians to stop them falling into the hands of people smugglers.

As part of their border protection policy, the coalition has pledged to spend $20 million on a "community engagement program" in Indonesia, which includes the boat buyback scheme.

The plan has been met with heavy resistance in Jakarta, and some scepticism back home.

Mr Abbott on Sunday defended the scheme, saying it was worth trying to get local villages in Indonesia working with Australia rather than the people smugglers.

But he admitted "it's possible" the government would never actually buy any boats at all.

"We may not buy boats back," he told ABC Television on Sunday.

But the opportunity to pay someone a couple of thousand dollars to stop a boat from being launched when the cost of one arriving in Australia was about $12 million would be "a shrewd investment".

The boat buyback plan was just one plank of the coalition's border protection policy, and would add to flexibility for Australia and Indonesia authorities on the ground, Mr Abbott said.

Federal Labor has rubbished the idea, pointing out Indonesia has three quarters of a million boats, and shipbuilders would make them faster than they could be bought.