THE chief constable of Cleveland Police last night took the extraordinary step of threatening to sue unnamed individuals who have accused him of using "undue influence" to appoint a new member of staff.

A furious Sean Price made the legal threat after the Independent Police Complaints Commission said it had launched an investigation into the allegations.

The IPCC said the allegation came to light during a review by Her Majesty's Inspectorate of Constabulary into the way some individuals within Cleveland Police Authority ''may have conducted some of its business''.

The inquiry is the second to involve Cleveland Police in the last six months.

A separate criminal investigation, under the jurisdiction of Warwickshire's chief constable Keith Bristow, is on-going into a number of people with current or past associations with Cleveland Police Authority.

A commission spokesman said: ''The IPCC is not actively involved in this criminal investigation, but is being kept informed about its progress.

''The IPCC's independent investigation will focus on the allegation that Mr Price used undue influence to have an individual appointed to a position within the police force.''

The chief constable, who has headed the force since 2003, hit back last night He said: ''I understand that this allegation relates to the recruitment process for a junior member of staff in late 2008.

''I completely refute the accusation, which I regard as malicious as I took no part in the recruitment process. I further believe the allegation is mischievous in seeking to cause comparison with recent events in other forces.

''I realise the IPCC need to investigate this matter and will assist in every way that I can.

''I want the matter to be cleared up as soon as possible and I am sure that everyone will realise the damage that such an allegation could have on my personal standing and confidence in the force.

''In addition I am taking legal advice regarding any action I may take in the future against those responsible for initiating and spreading incorrect information that defames my character.''

The chief constable has received support from Peter Race, the interim Chairman of Cleveland Police Authority.

He said: "We fully support his wish that this matter should be resolved at the earliest opportunity in both his interests and that of the Force as a whole."

The news came the day after Cleveland Police Authority appointed an interim chairman after previous chairman Dave Mcluckie stepped down earlier this month after a criminal investigation was launched.

Mr Price isn't the only chief constable to have been embroiled in controversy. Earlier this month, the chief constable of North Yorkshire, Grahame Maxwell, faced calls for him to quit after he admitted gross misconduct.