The Conservative leader of Norfolk County Council stepped down with immediate effect last night in an extraordinary new twist in the build-up to a standards inquiry into his conduct.

Derrick Murphy is to be brought before his own council's standards committee over his role in the sending of an email which appeared to undermine a fellow Tory council leader.

He said he was 'confident' over the outcome of the standards hearing and that he would soon be back as leader.

He said he remained chairman of the Conservative group and, following a positive outcome for him at the standards hearing, he would call a meeting of that group to seek their support for him to return as leader.

But a statement from County Hall said that in line with the party constitution, deputy leader Bill Borrett would be acting leader until such time as a new leader was appointed by the council.

Mr Murphy said it was his hope and expectation that his stepping-down would be temporary. If he won his case at the standards hearing, he would have to seek re-election.

In a day of drama Mr Murphy decided, after talks with senior colleagues, to step down as leader until after the standards hearing which he hopes will take place within the next fortnight.

In a statement sent to officers at the county council and fellow councillors, he said: 'I am writing to inform you that it is my intention to step down as leader of the county council until the standards committee hearing takes place into complaints against me which were highlighted in the Eastern Daily Press on January 8.

'As you may imagine my preparation for the standards committee hearing is taking a considerable amount of my time and attention at a time in the year when as leader I should be focused on working with my cabinet to prepare for the 2013 Budget.

'It is my hope and expectation that I will clear my name and return to the position as leader, but in the meantime, I am standing down as leader of the county council with immediate effect, for what I regards as a temporary period of absence.'

A second county council statement said Mr Murphy, council leader since October 2010, was stepping down as leader with immediate effect to concentrate his efforts on fighting the Standards Committee hearing, expected to be within a matter of weeks, into complaints brought against him.

It added: 'In line with the constitution, the Deputy Leader, Councillor Bill Borrett will be Acting Leader until such time as a new Leader is appointed by Council. This will happen in due course.'

Mr Murphy said he would not be involved in cabinet matters, would be foregoing his leadership allowance but continue to deal with issues which arise in his division.

The complaints surround an email sent by Kevin Vaughan, then political assistant to the Conservative group at County Hall, to BBC Radio Norfolk last April.

It was sent two days before West Norfolk Council leader Nick Daubney was to appear on Nick Conrad's show to discuss the King's Lynn incinerator, long a source of tension between West Norfolk and Norfolk County Council.

It suggested it might 'be pertinent information' for the broadcaster to know that the borough council leader was facing 'a serious leadership challenge' and that his authority had failed to procure alternative technology to the plant.

When the email came to light it sparked an independent investigation at County Hall, which concluded last summer that Mr Vaughan had acted on the wishes of leader Mr Murphy.

Mr Vaughan later resigned as the political assistant to the Conservative group and seven complainants – John Martin, Ron Cornell, Jenny Perryman, Joy Franklin, Christine Hall, Mark Russell and Stuart Wilkie – have alleged that Mr Murphy had failed to treat both Mr Daubney and Mr Vaughan with respect and that he had brought his office or the authority into disrepute.

Barrister Jenni Richards, QC, was appointed by the county council to compile a report and concluded she believed Mr Murphy did have a case to answer, which led to the scheduling of a standards hearing.

Mr Murphy, who represents Freebridge Lynn, is allowed to call witnesses to support his case at the hearing, and has said Mr Vaughan has agreed to appear on his behalf.

He said: 'My advocate contacted Kevin and asked if he would appear as a witness for me and he said he would. Read into that what you will, but here's a person these third parties are complaining I have behaved badly towards, willing to be a witness on my behalf.'

He added he wanted the hearing to be in public – a decision which will rest with the standards committee.

He said: 'I think it's very important that it is in public. There's a lot of evidence I want people out there to know about. Justice needs to be done and justice needs to be seen to be done. That's why I'm keen that it's a public hearing.'

The standards committee consists of seven county councillors. Five, like Mr Murphy, are Conservatives, one is Liberal Democrat and one is Green. If the hearing concludes there has been a breach of the code, the committee could recommend to the council that Mr Murphy be removed from his position.

Other sanctions available to the committee, should it find a breach, include the option to reprimand or censure him, to order training in ethics or standards or to prevent him from having access to council premises.

dan.grimmer@archant.co.uk