One of the suspects in the Woolwich murder case was arrested in Kenya in 2010, the Foreign Office has confirmed.It said Michael Adebolajo was arrested there and it gave consular assistance "as normal" in the circumstances.He was believed to have been preparing to train and fight with Somali militant group al-Shabaab, Boniface Mwaniki, head of Kenya's anti-terrorism unit, told the Associated Press.He said Mr Adebolajo was arrested with five others and later deported.The Kenyan government had previously denied he had ever visited the country, but spokesman Muthui Kariuki said there had been some confusion as he was arrested under a different name.Mr Adebolajo, 28, and a second man, Michael Adebowale, 22, were arrested on suspicion of the murder of soldier Lee Rigby in Woolwich on Wednesday.They remain in custody in hospital in a stable condition after being shot and wounded by police at the scene after the killing.Three further men, aged 21, 24 and 28, were arrested in London on Saturday evening on suspicion of conspiracy to commit murder - a Taser was used on two of them.Home Secretary Theresa May told the BBC's Andrew Marr programme "500 officers and others" were working on the case, including counter terrorism officers brought in from elsewhere in the country.Senior Whitehall sources have previously confirmed to the BBC both suspects arrested at the scene of Drummer Rigby's killing were already known to security services.When asked if there were mistakes made by the security services in dealing with this case, Mrs May said: "What we have is the right procedures which say when things like this happen we do need to look at whether there are any lessons to be learned."A special taskforce is being set up to "look again" at the government's strategy for dealing with extremism and radicalisation.It will be chaired by the prime minister and include senior cabinet ministers and security chiefs.On Friday, a friend of Mr Adebolajo, Abu Nusaybah, told the BBC's Newsnight that the Woolwich suspect travelled to Kenya last year "to study".But instead, he said, Mr Adebolajo told him he had been detained by "Kenyan troops", interrogated in a prison cell and "beaten quite badly".Upon his return, Abu Nusaybah said Mr Adebolajo was approached by MI5 who asked him to work for them - a request he rejected.