But critics say the offer is "collaboration" with a regime that has come under fierce criticism for its human rights record.

Mr Abbott's laudatory assessment of Sri Lanka's human rights progress since the end of its civil war was in stark contrast to British Prime Minister David Cameron, who infuriated the regime by visiting displaced families in the formerly war-affected north and demanding an international inquiry into war crimes.

At a Colombo dock on Sunday, Mr Abbott said Australia would give two Bay-class patrol boats, recently retired from surveillance service in Australia, to the Sri Lankan navy to use as interdiction vessels, capturing asylum-seeker boats before they are able to leave Sri Lankan waters. "People smuggling is a curse. It is an evil trade … the promises that people smugglers offer are promises of death, not life," he said.

Critics condemned the gift, which will cost Australia about $2 million.

"The Prime Minister's silence on human rights abuses in Sri Lanka was inexcusable complicity, but this is nothing less than collaboration and it is abhorrent," Greens leader Christine Milne said.

Labor frontbencher Tony Burke said he wanted to see details of the agreement governing the ships' use. "I'm not sure how it works … because you are not dealing with a transit country,'' he said. ''There

may be some people who claim to be directly seeking asylum."

Refugee Action Coalition spokesman Ian Rintoul said the co-operation sent a message to the international community that Australia accepted continuing human rights abuses in Sri Lanka.

The patrol boats will be delivered to Colombo, newly refurbished, by the middle of next year. Details of the agreement, including what weaponry the ships could carry and how they could be deployed, have not been made public.

Chief of Sri Lanka's navy Vice-Admiral Jayanth Colombage said the vessels would improve the navy's surveillance capabilities. ''The ships will be put into good use, to maintain the freedom of the Indian Ocean from any kind of maritime crime,'' he said.

Mr Abbott dismissed concerns the Sri Lankan navy could not be trusted as a partner in stopping people smuggling.

Four Sri Lankan sailors, including a senior officer, are under arrest on suspicion of being key players in the country's largest, and most profitable, smuggling racket, and more are being investigated.

Since the arrests, the number of people leaving Sri Lanka by boat has fallen by 90 per cent. ''While I regret … that at least on the face of it there appears to have been some improper behaviour, the fact the Sri Lankan government is cracking down hard on this gives me great confidence,'' Mr Abbott said.

Others in Sri Lanka allege that naval complicity in people smuggling operations is systemic and reaches to senior levels of the force.

Sri Lanka, as host of the Commonwealth Heads of Government Meeting this weekend, has faced intense scrutiny over its human rights record, in particular over allegations of war crimes committed by government forces at the end of the country's civil war in 2009, and of continuing abuses, including abductions, torture and extrajudicial killings by state forces, land seizures and repression of political dissent.

A United Nations report found in the final months of fighting in 2009 ''credible allegations … of violations … some of which would amount to war crimes and crimes against humanity'', committed by government forces and the rebel Tamil Tigers.

Australia told Sri Lanka at the UN last year it must ''take action to reduce and eliminate all cases of abuse, torture or mistreatment by police and security forces … and eliminate abductions and disappearances''.

But Mr Abbott said significant progress had been made since the end of conflict.

By contrast, Mr Cameron was critical of reconciliation efforts and of continuing abuses allegedly at the hands of state security forces. He infuriated Sri Lankan President Mahinda Rajapaksa by visiting the former war zone city of Jaffna, meeting the families of people who have disappeared and those who have had their land seized by the military.

Sri Lanka has refused any international oversight of its inquiry into disappearances.