BBC News with Michael Powles The President of Haiti Rene Preval says tens of thousands of people are (feared) dead following Tuesday's earthquake which destroyed much of the capital Port-au-Prince. Schools and hospitals were among the buildings that collapsed. Survivors have been (roaming) the rubble-strewn streets of the capital, injured and unable to comprehend the devastation. Paul Adams has more. Almost 24 hours after the quake struck, it's still proving very difficult to assess the scale of this disaster. But the images, voices and Internet postings (pouring) out of Haiti all paint the grimmest of pictures. The capital of the poorest country in the western hemisphere has been devastated. Even its grandiose presidential palace built by the US army core of engineers has collapsed. As many as two million people live close to the epic center, many of them in teeming slums that cling precariously to steep (unstable) hillsides. The senior adviser to the Haitian prime minister told the BBC the focus would be on emergency assistance. She said she didn't know anyone in Port-au-Prince with a home now safe to live in. The Haitian president says the head of the United Nations mission to the country Hedi Annabi was killed in the earthquake. He said Mr Annabi's body was found in the UN headquarters in Port-au-Prince which collapsed when the quake quick struck. However, the UN says it has no (confirmation) of his death. President Obama has promised full American support for Haiti to help it recover from the earthquake. He said "We have to be there for them in their hour of need". Officials in Washington said US navy ships in the region had been told to be ready themselves. The UN's Emergency Relief Coordinator John Holmes said international (rescue) teams were already on the ground. "The Chinese search and rescue team has already arrived at the airport at eastern Port-au-Prince. I believe two US teams will arrive this afternoon and perhaps two more, tomorrow hopefully with ,uh, heavy equipment as well as experts and dogs and so on. Others are on the way from many countries. So, that kind of help is beginning to arrive at the cottages (desperately) need it and as you all aware, every hour counts in this kind of situation when people are trapped under the rubble in desperate need of being rescued." Scientists say the earthquake in Haiti has had a particularly (severe) effect because most people weren't expecting it. There has been no significant earthquake there for more than 200 years. Our science reporter Matt Mcgrath looks at the factors that have caused such devastation. There are three elements to this earthquake that in (combination) explained its deadly nature. First is the power. A magnitude 7 is (equivalent) to the energy given off by half a million tons of high explosives. The second is the location, just 10 kilometers beneath the earth and very near the capital city. Closeness to the surface is a key factor contributing to the (severity) of the ground shaking caused by a tremor. The final factor is the lack of awareness among the population and the government about the possibility of an earthquake given that has been so long since the last major one. Matt Mcgrath reporting You're listening to the World News from the BBC in London. The opposition in Guinea says it would be best if the military leader Captain Moussa Dadis Camara stays out of politics for a while. An opposition spokesman told the BBC that what he (described) as agitators in Captain Camara's entourage who tried to use him to pursue their own interests. On Tuesday, Captain Camara flew to Burkina Faso from Morocco where he was being treated for injuries received in an assassination attempt last month. A high court in Nigeria has ruled that the (vice) president has the right to perform all duties on behalf of the president without a formal transfer of power. President Umaru Yar'Adua has been receiving medical treatment in Saudi Arabia since November, a move which has caused unease in Nigeria. From Abuja, Caroline Duffield has this report. When President Yar'Adua was (rushed) to hospital, he didn't formally hand presidential powers to his deputy. Now in the first of full-court cases, a judge has ruled that the current situation is legal. Justice Daniel Abutu said that the vice president is able to perform all duties on behalf of the president, and crucially he said that no formal transfer of presidential powers by letter was necessary for that to happen. He said a formal transfer was only at the president's (discretion). Israel has formally (apologized) to Turkey for a breach of diplomatic manners that threatened to open a serious rift between the two countries. The row started while Israeli angered at alleged anti-Semitism in a Turkish television series, but deepened when Israel's Deputy Foreign Minister Danny Ayalon publicly (humiliated) the Turkish ambassador when delivering a protest. The heads of four of the biggest American banks have told public inquiry that they underestimated the severity of the financial crisis which started in 2008. At the congressional hearing, the chiefs said they regretted any risky (behavior) or poor decisions made by them. But they also said that they had done much to repair the damage by reining in pay and bonuses.