* Concerns over rights overshadow Commonwealth summit
* Some leaders missing from biennial meeting
* Sri Lanka defends its record on rights
COLOMBO/JAFFNA, Sri Lanka, Nov 15 (Reuters) - Crowds of protesters met British Prime Minister David Cameron in the north of Sri Lanka on Friday, some surging towards his vehicle brandishing photos of relatives lost in the country's long civil war that ended four years ago.
Cameron visited the city of Jaffna in the ethnic Tamil- dominated region of the island after attending the opening ceremony of the Commonwealth summit in the capital Colombo. The biennial meeting of mainly former British colonies has this year brought intense scrutiny of Sri Lanka's human rights record.
"I think it's important to shine a spotlight on what's happened in this country and to speak up against abuses that have taken place," he said in a muddy shanty town of people pushed off their own land by the military 23 years ago.
Rival protesters met Cameron on his tour of the town, including Tamils seeking his support in locating missing relatives and also government supporters who waved placards that read "We are not a colony" in opposition to his visit.
Sri Lanka's President Mahinda Rajapaksa had hoped the Nov. 15-17 meeting, which two heads of government have boycotted, would prove an advertisement for progress and economic growth in the island state of 21 million off India's southern tip.
Instead, the build-up to the summit has been overshadowed by allegations of state-sponsored rape and torture, and by political pressure, including from Cameron.
Separatist Tamil rebels with a preference for suicide bombers battled government forces for 26 years until an army offensive crushed them in 2009.
A U.N. panel has said around 40,000 mainly Tamil civilians died in the final months of the offensive. Both sides committed atrocities but army shelling killed most victims, it concluded.
The United Nations wants an international inquiry into allegations of war crimes in the final months of the conflict.
Opening the summit, Rajapaksa defended the government after saying this week it had "nothing to hide".
"We in Sri Lanka are stepping into a new era of peace, stability and premium economic opportunities," he told government leaders and officials from 49 countries.
"In ending terrorism in 2009 we asserted the greatest human right, the right to live."
After Cameron returned from Jaffna he met Rajapaksa and raised concerns about displaced people, land issues, the military presence and devolving powers to the north, the Sri Lankan government said in a statement.
Rajapaksa told him it was only four years since the war had ended and the country needed more time to overcome its problems.
BRITISH PM VISITS NORTH
Many buildings in Jaffna are still bombed out skeletons despite a surge of reconstruction. While there, Cameron visited a recently rebuilt library and a Tamil newspaper often targeted by unknown gunmen who have killed six journalists since 2006.
At the library his car was nearly surrounded by a group of mainly women protesters who say their loved ones were taken by the army during the war and have never been returned to them. The women pressed pictures of the missing against the windows of a media bus and surged towards Cameron's vehicle after pushing through police lines.
Some observers warn that the repressive climate in the north and slow progress on demands for greater autonomy risk stoking fresh violence. Military seizure of land is one of the most sensitive issues in north.
At the Kannagi camp, where about 500 people are yet to be resettled on land occupied by the army despite promises they could go home, Cameron walked though narrow, muddy rows of tin shacks where he was mobbed by families speaking in Tamil.
"The war is over," he said to a government official walking alongside. "Why is it taking so long to resettle?" The official replied that the resettlement was under way.
Officials in Colombo have expressed frustration at what they see as interference from abroad in the run-up to the Commonwealth meeting and say Sri Lanka is on a path to reconciliation, aided by strong economic growth.
The government has also dismissed accusations of ongoing rights violations, which it says are part of a campaign by rebel sympathisers to tarnish its image and detract from the summit.
The Commonwealth, comprising 53 countries, has little power, but wields some influence in mediating disputes between members.
Canadian Prime Minister Stephen Harper said last month he would skip the summit over rights abuses, including alleged disappearances and extra-judicial killings, and Mauritian Prime Minister Navinchandra Ramgoolam later joined the boycott. As a result of not attending, Mauritius will no longer host the next summit in 2015, Ramgoolam said on Friday.
Prime Minister Manmohan Singh of India, whose population of 1.2 billion dwarfs the rest of the Commonwealth combined, also did not travel to Colombo, although it was partly due to domestic pressures. His foreign minister is taking part.