The existing system to root out police wrongdoing is being undermined by poor-quality investigations and lacks the powers and resources to get to the bottom of serious cases of corruption and misconduct, according to a damning report published today.

The body set up to investigate police misconduct since 2004, the Independent Police Complaints Commission (IPCC), is not yet capable of being the powerful watchdog it should be, according to a committee of MPs.

While a series of incidents have tested the public’s confidence in police - including the death of Ian Tomlinson in 2009, the Hillsborough tragedy cover-up and the continuing probe into conspiracy claims against former Government chief whip Andrew Mitchell - the report found that the IPCC too often made public mistrust of police worse, not better.

IPCC inquiries into alleged police wrongdoing start too late and take too long, according to the Home Affairs Select Committee. The finding came as the IPCC conducts an inquiry into the Hillsborough tragedy - its biggest ever - which will involve analysing the roles of some 2,000 people.

The IPCC, which has seen its budget cut by 13 per cent over four years, is "woefully underequipped and hamstrung," in achieving its objectives, with less funding than the professional standards department of the Metropolitan Police. The report said the law should be changed so that officers are routinely questioned after a death involving police.

"It has neither the powers nor the resources that it needs to get to the truth when the integrity of the police is in doubt," the report said.

The inquiry highlighted claims that the IPCC failed to locate evidence and uncritically accepted police explanations for missing evidence, lacked the skills and experience of qualified lawyers and prosecutors, and was too slow in responding to complaints and conducting investigations.

The IPCC has been criticised by campaigners including Doreen Lawrence, the mother of the murdered black teenager Stephen Lawrence, who said she had "no confidence whatsoever," in it. The organisation has faced calls for it to be scrapped, but the MPs said it should instead be given more money and greater powers to investigate other agencies.

Deborah Coles, co-director of Inquest which works with families of those who have died in custody, said: "The IPCC systematically fails to hold the police to account for wrongdoing."

The MPs extended their damning indictment of the IPCC’s abilities to that of police forces’ own disciplinary units. When the IPCC investigated appeals from the public into the way that forces had handled their complaints, it found that police had been wrong in 31 per cent of cases.

The Police Federation - which represents officers up to the rank of inspector - told the inquiry that the IPCC failed to intervene in cases where professional standards departments had "allegedly conducted a poor, biased or even corrupt investigation."

"A strong watchdog is vital to get to the truth but the IPCC leaves the public frustrated and faithless," said committee chairman Keith Vaz.

Dame Anne Owers, chairwoman of the IPCC, said: "This report recognises that we do not yet have the resources or powers to do all that the public rightly expects and needs from us."

The Home Office said it would shortly announced plans to improve public trust in the police. "Improving police professionalism and integrity are at the cornerstone of the sweeping reforms we are making," it said. .