Up to 280,000 failed asylum seekers live in Britain costing taxpayers hundreds of millions of pounds because the immigration service has yet to deport them, the government's spending watchdog said on Tuesday. The cost of supporting rejected claimants was put at 308 million pounds for 2003-2004, a touch over the 300 million pounds the immigration service spent on enforcement and deportations. Britain's immigration minister acknowledged the failings, but said steps were being taken to address deficiencies. "We are speeding up the decision making process, but there is still a way to go," Tony McNulty told BBC radio. The exact number of failed applicants was unclear because the immigration service's computer systems do not have complete records, but the National Audit Office (NAO) said the figure was likely to be between 155,000 and 283,500. The figures are on top of the estimated 310,000 to 570,000 illegal immigrants the government said in June were thought to have made their home in Britain.