The head of the civil service has dismissed claims that there are plans to cut the number of Whitehall mandarins by 90%.

Sir Bob Kerslake, the head of the home civil service and permanent secretary at the Department of Communities and Local Government,

"For the avoidance of doubt there are absolutely no plans to cut the civil service by either 70 or 90 per cent," he said on Friday morning.

Sir Bob was responding to an article in the Daily Telegraph that claimed the government intended to identify and fire under-performing civil servants after ranking them in order of ability.

According to the paper ministers have become increasingly frustrated at what they see as the "lazy" officials that staff their departments.

There are currently 434,000 civil servants who work for government departments and quangos.

Steve Hilton, the prime minister's soon-to-depart director of strategy, is said to believe that the country could be run with only 10% of that number.

And according to the Telegraph he suggested testing the theory by cutting the number of civil servants in one department by 70% to see how it coped - a plan rejected this morning by Sir Bob.

However he did acknowledge that some of his staff may not be up to the job.

"The vast majority of civil servants work hard and do a good job. Like others we can do better at tackling poor performers," he wrote on Twitter.