A serving MP is at the centre of at least one of 14 inquiries by the Independent Police Complaints Commission, amid claims that Scotland Yard sought to cover up child sexual abuse by men in positions of power, the Observer understands.

The politician’s name was discovered in correspondence collected during a raid on the house of a member of a paedophile ring in the early 1990s. It is claimed that a police investigation into those papers, which contained other high-profile names, was not permitted to follow up all the leads uncovered during the raid.

According to one witness who has given evidence to Scotland Yard’s directorate of professional standards, a senior police officer explained to social services after the raid that a thorough investigation “was not going to happen” on the order of those “up high”.

Sources claim that the MP named in the correspondence was being volunteered by one paedophile to another as a person who could look after obscene images of children. There is no evidence that the MP was aware that he was being volunteered, nor that he played any role in the alleged attempt to stop the subsequent police investigation.

It is understood that the senior police officer involved denies saying to anyone that pressure had been put upon him to close the inquiry. However, a source said witnesses to the alleged cover-up believe more should have been done to pursue the truth.

Last Monday the IPCC announced that it was investigating 14 referrals detailing allegations of corruption in the Metropolitan police in relation to child sex offences dating from the 1970s to the 2000s. The allegations, referred to the IPCC by the Met, include suppressing evidence, hindering or halting investigations and covering up offences because of the involvement of MPs and police officers.

Scotland Yard took witness statements late last year over a failure to properly investigate leads emanating from the raid on the home of a notorious paedophile in the West Midlands, where the MP’s name was uncovered in a letter.

At least one person asked to give evidence to Scotland Yard named the MP in their formal statement, the Observer has learned. That witness was approached by the directorate of professional standards to give evidence, having been a central figure in attempts to uncover child sexual abuse and having aided Operation Fairbank, which was launched in 2012 to investigate allegations that high-profile political figures had been involved in organised sexual abuse. A spokesman for the IPCC said he could not comment.

In a case yet to be referred to the IPCC, Northamptonshire police are also investigating claims that local police found child sex abuse videos in the car of the late MP Cyril Smith in the 1980s but took no action after he made a phone call to London from a police station.

Separately, further inquiries are being carried out into whether detectives were told to limit a child abuse investigation centred on the former MP Lord Janner. A home belonging to the 86-year-old peer, who was a Labour MP in Leicester for 27 years, was searched in 2013. Last year it was reported that in 1989 a detective sergeant had been told not to arrest Janner or search his home. The IPCC has said that more investigation is needed. Leicestershire police said internal inquiries had been made before the matter was referred to the commission.

Earlier this month the home secretary appointed Justice Lowell Goddard to head a separate public inquiry into whether “public bodies and other non-state institutions have taken seriously their duty of care to protect children from sexual abuse in England and Wales”. The reformed independent inquiry into child abuse will be on a statutory footing “to compel witnesses to determine whether state and non-state institutions have taken seriously their duty of care to children”.