COLOMBO (AFP) - Commonwealth leaders signed agreements on Sunday on issues such as poverty and development as they staged a show of unity after a summit in Sri Lanka dominated by a bitter dispute over war crimes.

After a three-day meeting in Colombo, Sri Lankan President Mahinda Rajapakse announced a declaration had been signed by the Commonwealth's 53 member nations after a summit which he said had been characterised by "fruitful discussions".

But he was again forced on the defensive and warned his critics against pushing him "into a corner" by setting an ultimatum to address war crimes allegations by next March.

"I am happy with the outcome we have reached at this CHOGM," said Rajapakse, who has spent much of the summit having to fend off allegations that his government's troops killed as many as 40,000 civilians at the end of the country's 37-year conflict.

Outlining the agreements inked by Commonwealth leaders, he said there had been widespread agreement on a series of issues - particularly on ensuring that economic growth does not come at the expense of equality.

"Achieving growth with equity and inclusive development must be one of the priorities of the Commonwealth," said the Sri Lankan president.

"Issues covered in the communique include development, political values, global threats, challenges and Commonwealth cooperation."

While only 27 heads of government attended this year's meeting, Malaysian Prime Minister Najib Razak said the summit had helped strengthen the organisation of mainly English-speaking former British colonies.

"I sense there is a reaffirmation of the spirit and ideals of the Commonwealth ... the core values of the Commonwealth, namely democracy, the rule of law and human rights," Najib told reporters.

The Malaysian prime minister said there was a general recognition among leaders of "the fact that we are different but should not be divided".

"There was a reaffirmation of the spirit and willingness of wanting to stay together as a unique collection of nations."

The summit was dealt several body blows before it began, with the leaders of Canada, India and Mauritius deciding to stay away to protest at Colombo's rights record.

Australian Prime Minister Tony Abbott, who was handing over the chairmanship of the Commonwealth to Sri Lanka, acknowledged "more needed to be done" to address concerns about its rights record but said he wanted to be "good mates" with Colombo.

According to the United Nations and rights groups, as many as 40,000 civilians may have died as troops loyal to the mainly Sinhalese government routed the Tamil Tiger rebel movement in its last stronghold in Jaffna in 2009.

Sri Lanka has refused to allow foreign investigators onto its soil, but Cameron warned Rajapakse he would lead a push for an international probe through UN bodies unless an internal inquiry produces credible results by March.

"Let me be very clear, if an investigation is not completed by March, then I will use our position on the UN Human Rights Council to work with the UN Human Rights Commission and call for a full, credible and independent international inquiry," said Cameron on Saturday.

But Rajapakse reiterated on Sunday that Sri Lanka would not bow to pressure and would complete its own inquiries in its own time.

"This is not something you can do overnight. You must also respect our own views without trying to push us into a corner, so please be fair," he said.

"We have suffered for 30 years, that's why they (the people of Sri Lanka) want a new life. That's why people elected me." The largely pro-government press in Sri Lanka acknowledged that debate about Colombo's rights record had soured the summit.

Ceylon Today said Cameron's push for UN action had ensured "the festive mood at the Commonwealth parley turned sour", bemoaning how "media obsession over the host country's human rights record had overshadowed the official business".

Mauritius had been due to host the next summit in 2015 but it withdrew in protest against Sri Lanka's rights record.

Malta will now step in as hosts, the organisation's top official announced.

"The prime minister of Malta has invited the Commonwealth to hold CHOGM (Commonwealth Heads of Government Meeting) 2015, with Malta as the venue," Secretary General Kamalesh Sharma said.

"It (the offer) was received by all members with acclamation."