Blair aides' power under attack

Mr Campbell, who is Tony Blair's head of communications, and the prime minster's chief of staff, Jonathan Powell are both politically appointed civil servants.

Normally that would mean they cannot issue orders to civil servants who are supposed to be impartial.

But Mr Campbell and Mr Powell were both made exceptions to that rule when Labour first took power in 1997.

Now Baroness Prashar, the head of the Civil Service Commission, says that not only should their right to give orders to civil servants be removed but that no special adviser should have "executive power".

She acknowledged that that special advisers had an "important role" but said that role should be clearly set out in legislation to ensure boundaries between them and their civil service counterparts.

A civil service bill should be introduced in the next Queen's Speech, she argued.

"I do not think it is appropriate for special advisers to have the authority to instruct civil servants," she said.

"They should not have executive powers. It is not a question of personalities or individuals."

Spingate

Baroness Prashar's intervention comes in the wake of the row over the part played by Mr Blair's office in the wake of the death of the Queen Mother.

Mr Campbell faced calls for his resignation amid claims that Number 10 had exerted pressure on senior parliamentary official Black Rod over the prime minister's role at the Queen Mother's lying-in-state.

That followed the long-running "Spingate" row which eventually saw the departure of special adviser Jo Moore followed some weeks later by former transport secretary Stephen Byers.

Ms Moore famously sent a memo to staff at the department that 11 September was a good day to bury bad news.