Scotland Yard commissioner Sir Paul Stephenson has bowed to demands from his watchdog body and will attend an emergency session on Thursday to convince critics that police have stopped bungling the phone-hacking crisis that has dented the force's reputation.

Earlier this week the Met said Britain's top officer would not be present and some members of the Metropolitan Police Authority warned his failure to attend would be seen as a discourtesy and sour relations.

The force is trying to pick itself up from Tuesday's damaging session of the home affairs committee where assistant commissioner John Yates was told by MPs that his evidence was "unconvincing", and former assistant commissioner Andy Hayman's evidence went down so badly with MPs that some of them openly laughed at him and asked if he was corrupt, which he categorically denied.

Hayman hit back on Wednesday and accused MPs of a "lynch mob mentality" and of an "appalling display" during which they treated him like "dirt". But one of Britain's top officers has criticised Hayman for dining with News International executives as his force investigated them for alleged criminal offences.

In other developments, London's mayor Boris Johnson gave his backing to Yates and the prime minister announced the Met would appoint a senior public figure to advise them on how to interact with the media.

Thursday's session of the usually obscure MPA Strategic and Operational Policing Committee will be the first time the commissioner has formally answered questions after the phone-hacking scandal exploded.

Stephenson, who met with the PM on Tuesday evening to discuss the crisis, was warned by Labour lead MPA member, Joanne McCartney, that he has questions to answer about his handling of the phone-hacking scandal.

McCartney said: "He will have to account for himself. Members are not gunning for the commissioner but he needs to answer questions."

Green party MPA member Jenny Jones became the first one to say the commissioner should quit over the Met's errors in the phone-hacking crisis. While a minority view on the MPA, it is a sign of growing unease among the watchdog body.

Jones said: "He has not shown enough leadership on this. He has not shown that he has taken the issue at all seriously.

"The commissioner treats us with contempt. When somebody treats the body supposed to hold them to account with contempt, they are in the wrong job."

There was some welcome news for John Yates, whose evidence on Tuesday before MPs about why he decided in 2009 and 2010 not to reopen the phone hacking investigation, fuelled calls for his resignation.

London mayor Boris Johnson, who has dismissed the phone-hacking allegations in the Guardian as "codswallop" and part of a Labour conspiracy, backed the assistant commissioner who runs the Met's counter terrorism command.

Johnson said: " I have to take a judgment on the case and I believe that John Yates is doing a very important and effective job in leading the struggle against terror in the city and, in my view, it is vital that he is allowed to continue to do that."

There were no statements of support for Andy Hayman who was in charge of the department that conducted the first and flawed police-hacking investigation.

Hugh Orde, president of the Association of Chief Police Officers said Hayman had been wrong to dine with News International executives as his force investigated them.

Orde told the BBC: "In those precise circumstances it seems an unwise decision."

Orde also attacked NI for trying to thwart police investigations: "This was a global company that had some responsibility and what we have here is the police service of this country, probably one of the most accountable services in the world, standing up and being counted.

"What we don't see yet is equal transparency or explanation from a very large multinational company who should frankly be explaining why they withheld information from such a serious investigation."

Hayman told LBC Radio he was treated like a "bit of dirt" by the home affairs committee and claimed the Labour MP Chris Bryant, who was sitting in the audience, had laughed loudly while he gave evidence.

Hayman said: "I've been through the mill several times in court, in journalistic interviews. I've never been treated like yesterday.

"There was cat-calling, there was loud laughter from the wings by Chris Bryant. It was an appalling display from them.

"The irony really is that they don't like being treated in this way disproportionately and yet they're prepared to put us through that.

"I think all four of us were up for tough questioning, but not on that sort of basis. And to be accused, as I was, of being a dodgy geezer, which is probably on the basis on my accent, I think that's a really poor show."

Hayman added: "Despite trying to actually be helpful to them, all they want to do is score points and most of that is political and with this sort of lynch mob mentality.

"Bring on the formal inquiry with a respectable judge, when we can actually get some sense out of this.

"I'm not asking for special treatment, I just ask for a little bit of respect and not to be treated basically as a product because of the way in which you speak."