The UK has issued a travel ban to more than 20 Kenyan citizens accused of corruption, the High Commissioner says. Rob Macaire said the ban was a last resort, pointing out that no senior official had ever been convicted of corruption by a Kenyan court. He was speaking at the launch of a new campaign aimed at tackling corruption. The names have not been made public but they are thought to include senior civil servants, politicians and businessmen. President Mwai Kibaki was first elected in 2002 on a pledge to end corruption but his government has since been accused of lacking the political will to tackle corruption. Mr Macaire pointed out that Britain's Serious Fraud Office (SFO) had dropped its investigations earlier this year into the "Anglo-Leasing" affair, in which contracts worth some $100m were awarded to firms which did not exist. The SFO said it was dropping the case because of a lack of co-operation from Kenyan agencies. In February, Kenya's attorney general blamed the delays on the country's judicial system. Mr Macaire acknowledged Kenya's progress in passing anti-corruption laws, but he argued that they are meaningless without the values to underpin them. The US has recently banned some Kenyan officials from travelling there, accusing them of blocking political reforms after deadly post-election violence in 2008.