Cameron defends trip to "imperfect" Commonwealth summit David Cameron in Calcutta, India, on Thursday en route to Sri Lanka The UK prime minister has said the Commonwealth is "imperfect," but defended his trip to Sri Lanka to attend the organisation's heads of government meeting, which begins on Friday. David Cameron landed in Colombo on Thursday night in the middle of two rows, one with the Sri Lankan government about his criticisms of its record on human rights, and one with the Labour party for attending the gathering. Mr Cameron said the trip gave him a chance to raise concerns over alleged war crimes committed during, and in the aftermath of, Sri Lanka's civil war. But he told the BBC: "The choice I have is a binary one: to go to that conference, or to leave that conference and to leave an empty chair." He added: "If your argument is that the Commonwealth is imperfect, then yes, of course it is." The prime minister's dilemma comes as he tries to defend both the Commonwealth, which the government sees as a key part of the UK's diplomatic power abroad, and the position of the Prince of Wales, who for the first time will sit in the Queen's place as head of the organisation. In an effort to show his trip does not mean the British government is condoning the Sri Lankan government after accusations of war crimes and press harassment, Mr Cameron has made forthright criticisms of the regime, calling for an investigation into those allegations. But his words have triggered anger from his Sri Lankan hosts. Keheliya Rambukwella, the country's communication minister, told the BBC: "We are a sovereign nation. You think someone can just make a demand from Sri Lanka. It can be a cordial request. We are not a colony. We are an independent state. Back in Britain, the prime minister came under attack from Ed Miliband, the Labour leader, who has argued that Mr Cameron should have followed the examples of his Canadian and India counterparts, Stephen Harper and Manmohan Singh, and boycotted the meeting. Mr Miliband said on Thursday that having arrived in Sri Lanka, the prime minister should now try to oust Mahinda Rajipaksa, the Sri Lankan president, from his role as Commonwealth chairman. The Labour leader said: "Unless we see . . . meaningful change on human rights in Sri Lanka, David Cameron should work with other Commonwealth leaders on securing an alternative candidate." Mr Cameron is not the only person trying to resolve the problems caused by Britain's decision to attend. William Hague, the foreign secretary, on Wednesday appealed to G.L. Peiris, the Sri Lankan foreign minister, to loosen controls on foreign journalists. This came after a film crew from Channel 4 was prevented from travelling to the Tamil north of the country, where many of the war crimes are alleged to have occurred. The row is symptomatic of problems facing the prime minister as he seeks to make trade and diplomatic influence the focal point of British foreign policy. Mr Cameron will go to China this year, showing that relations have finally thawed after the premier angered the Chinese government by meeting the Dalai Lama in London last year. Once again, the prime minister is likely face criticism for ignoring the country's lack of respect for human rights but ministers believe such trips are vital for helping to boost British exporters and economic recovery.