The UK Border Agency (UKBA) has cut too many staff too quickly and is now having to hire extra people and increase overtime to meet demands, Whitehall's spending watchdog said today.

Instead of slowing down staff cuts when it emerged an automated system designed to save money was both a year late and tens of millions of pounds over budget, the troubled agency increased the speed of its planned changes, the National Audit Office said.

More than 1000 staff over and above the planned reductions were lost last year, performance dropped and there is little evidence of the strong leadership needed to resolve the problems, the report added.

Border Force staff working at Heathrow Airport, one of its most high-profile and oft-criticised operations, also appeared reluctant to take up changes.

Some 22,580 staff were employed by the UKBA in April last year, but this had dropped to 20,469 by this April, figures showed. A Home Office spokesman said: "We're under no illusions about the scale of the challenge in transforming the UK Border Agency and Border Force and we have already saved huge sums of taxpayers' money, overhauled our business planning and improved performance."