London's police must end their cosy relationship with the media that has damaged their reputation and seen officers leaking confidential information to journalists in late-night drinking sessions, a report said on Wednesday.

The close ties, exposed by the initial lack of investigation into the illegal behaviour of some of Rupert Murdoch's journalists, had caused serious harm, said the report by Elizabeth Filkin, a former commissioner into parliamentary standards.

She warned officers to avoid flirty journalists who plied them with drink to get stories.

Alcohol. Late-night carousing, long sessions, yet another bottle of wine at lunch - these are all long-standing media tactics to get you to spill the beans. Avoid, said the report.

It is clear ... that there is a range of contact that is 'not permitted' and which, if unregulated, will continue to cause damage to the MPS (London's Metropolitan Police Service) and the public, it added.

The report was ordered by the government in the wake of revelations that the News of the World tabloid, owned by an arm of Murdoch's News Corp, had hacked into the phones of thousands of people, including celebrities and murder victims.

The case shook Britain's powerful media and the police - who were accused of failing to investigate the allegations properly for several years.

It was also an embarrassment for British Prime Minister David Cameron, who had hired a former News of the World editor as his spokesman.

At the height of the scandal in 2011, the top two police officers at the Metropolitan Police Service quit over their handling of the case.

The second to go, assistant commissioner John Yates, had dismissed demands for a new probe in 2009 after just eight hours of reconsidering the case.

Filkin told a news conference on Wednesday that she could not say for certain that the police had failed to investigate the phone hacking because of the ties to Murdoch's company, but said that was certainly the perception among the public.

That was the greatest concern for me, she said. The Met needs to bring about significant cultural change. There is a huge amount of work to be done.

In her report, Filkin quoted John Whittingdale, the chairman of a parliamentary committee which is also investigating phone hacking, who said the failure to investigate the allegations was appalling negligence if not corruption.

The only reason that I can think that the hacking enquiry was not fully pursued was that it was a story that the police did not wish to uncover. They did not want to damage their relationships with News International, he said, referring to Murdoch's British newspaper arm.

Filkin said she had heard allegations of police passing on tips to journalists in exchange for money, while other officers were seduced by the buzz of talking to reporters.

This situation appears to have compromised the capacity of both the police and the media to scrutinise the activities of the other, her report said.

The close relationship which developed between parts of the MPS and the media has caused serious harm, it added.

Metropolitan Police Commissioner Bernard Hogan-Howe told journalists the force would change its way of dealing with the media. There should be no more secret conversations, there should be no more improper contact. Meetings will no longer be enhanced by hospitality and alcohol, he said.

The report is the first of several due this year following the phone hacking scandal. The ongoing judicial inquiry looking into press standards will resume next week.

(Editing by Andrew Heavens)