David Cameron visits Brazil to boost trade links Prime Minister David Cameron is visiting Brazil today on a trip to boost UK trade links with one of the world's fastest growing economies. Mr Cameron was being joined in Brazil's commercial capital Sao Paulo by a 40-strong business delegation, along with trade minister Lord Green. During his two-day visit - his first to Brazil as PM - Mr Cameron will also hold talks with president Dilma Rousseff. Mr Cameron, who has made fostering trade links with emerging economic giants a key foreign policy priority, believes there are major opportunities for UK contractors to use the experience and expertise gained from the London Games to bid for work in Rio. The visit follows two days in New York in which he used a speech at the United Nations and an appearance on US TV's high-profile David Letterman show to highlight London's successful delivery of the 2012 Games and "bang the drum" for British business. Mr Cameron yesterday told the United Nations its hands were stained with blood for failing to stop the atrocities inflicted by the Assad regime in Syria. In his keynote address to the General Assembly the Prime Minister called on the whole international community to support moves to aid a transition of power in Damascus. His speech was a clear challenge to Russia and China, which have both blocked Security Council resolutions on Syria. Citing a recent Save the Children report documenting the torture and murder of children by regime forces in Syria, Mr Cameron told world leaders at the UN headquarters: "The blood of these young children is a terrible stain on the reputation of this United Nations. And in particular, a stain on those who have failed to stand up to these atrocities and in some cases aided and abetted Assad's reign of terror. If the United Nations Charter is to have any value in the 21st century, we must now join together to support a rapid political transition. The PM made clear he laid some of the blame for the Syrian atrocities at the door of Iran, which has backed president Bashar Assad, saying: "Assad has colluded with those in Iran who are set on dragging the region into wider conflict." He also restated the UK's position that Iran should continue to face "the full force of sanctions and scrutiny from this United Nations until it gives up its ambitions to spread a nuclear shadow over the world." Mr Cameron acknowledged there were doubts in the West over the momentum of the Arab Spring, but urged the international community to keep faith in the process of change in the Arab world. He said: "The Arab Spring represents a precious opportunity for people to realise their aspirations for a job, a voice and a stake in their own future. And we, in this United Nations, must do everything we can to support them. Following his address to the United Nations Mr Cameron was put through his paces on one of the USA's most influential TV chat shows. The PM was subjected to a bizarre quiz on British culture and history by Late Show host David Letterman. After touching on the issues surrounding Syria and the Arab Spring, Letterman grilled Mr Cameron on the composition of Rule Britannia, the origins of the Magna Carter and the make-up of the United Kingdom. He also revealed that it was thanks to TV that he was first recognised in the USA, when he was walking in the streets of New York and spotted by a passer-by who shouted: "Hey!