Sir Nigel Wicks is due to step down from his current role

Sir Nigel Wicks criticised the fact the government failed to implement recommendations he made in a previous report as a "missed opportunity".

The prime minister had been asked to define the role of special advisers.

Sir Nigel said: "There is considerable evidence trust in public office holders ... has fallen in recent years."

In his final annual report before he steps down as chairman of the committee for standards in public life, Sir Nigel said the government had a choice.

Erosion of trust?

Either ministers adopted the whole package or they could wait until "unfortunate events" forced their hands.

"This second approach would carry a cost: further erosion of public trust," he warned.

The committee wanted special advisers to be clearly separate from the civil service, but the recommendation has not been adopted.

The committee believed the government's response represented a seriously missed opportunity Sir Nigel Wicks

There was also concern expressed that ministers could be given a say in the hiring of civil servants.

Sir Nigel told BBC Radio 4's World At One he was puzzled by ministers' reluctance to follow the recommendations.

His committee had highlighted many of the issues about special advisers months before they wqere brought out in public hearings at the Hutton inquiry.

Risks

The former senior civil servant refused to comment on whether former Downing Street media chief Alastair Campbell should have chaired meetings of intelligence officers about the government's Iraq dossier.

But he said: "When it comes to the chairing of meetings, it's not clear that the boundaries are being respected and in those circumstances I think you have got to have very clear boundaries."

Sir Nigel argued that governments of all complexions needed to cope with a new environment after the decline in public deference and the decline of the belief "the powers that be" were right.

He was "very disappointed" the government had not yet published its promised draft Civil Service Bill.

Asked if he felt the civil service had been too politicised under Mr Blair's government, he said: "I think there are risks.

"But the point I emphasise is it's unhelpful to the way we govern ourselves if from time to time, whatever party is in office, there are these accusations of politicisation of the civil service."

Media role

The watchdog said the media too had responsibilities over falling trust in politics.

"We have a free press in this country and a free press decides what it wants to do," he said.

"But I think balance, following the story to the end, is a good precept to journalists."

Sir Nigel's committee launched its inquiry into special advisers after the then government spin doctor Jo Moore suggested 11 September 2001 would be "a good day to bury bad news".

In response to the latest report, the Cabinet Office has stressed the government is committed to producing a draft Civil Service Bill.