Hours after the CHOGM summit opened in Colombo, in a highly symbolic move, Cameron flew to Sri Lanka's Northern Province becoming the first foreign head of state since 1948 to do so.
His visit came against the backdrop of alleged rights violations in the war against the LTTE.
Cameron's car was surrounded by hundreds of Tamil protesters, who were held back by the military when they tried to hand him pictures of their missing loved ones.
"The stories I am hearing from the people here are often harrowing," he said.
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"I am the first President or Prime Minister to go to the north since 1948 (when Sri Lanka got independence from Britain). I want to shine a light on the chilling events there first hand. Proud to meet journalists risking lives to put a daily paper in northern Sri Lanka," he tweeted after meeting with the staff of Tamil daily 'Udayam' which had been repeatedly raided by the government.
"But it's only when you see it with your own eyes, it really brings home just how much you're suffering," Cameron said.
Cameron toured a library in Jaffna, which was repeatedly attacked and rebuilt during the conflict and met chief minister Wigneswaran of the Tamil National Alliance.
Cameron also visited the Sabapathipillai welfare centre for the war displaced in Jaffna's Chunnakam area and spent time talking to the displaced people having walked inside tin- roofed huts.
The Tamils' treatment at the end of the country's civil war dominated the run-up to the Commonwealth summit with the British Prime Minister defying calls for him to boycott the event in protest against alleged human rights abuses.
Cameron has insisted there should be a proper investigation into alleged Sri Lankan war crimes in the final months of the conflict which ended in 2009.