Untrained officers must never again be put in the frontline of policing public protests, according to a highly critical MPs' report on the G20 protests published today.

The conclusion from the Commons home affairs select committee inquiry into the G20 protests of April 1 follows admissions from senior Metropolitan police officers that some inexperienced officers, who were clearly quite scared, used "inappropriate force".

The report by the cross-party group of MPs says they "cannot condone the use of untrained, inexperienced officers on the frontline of a public protest under any circumstances".

Their inquiry also calls for the police to seriously consider whether they can continue with the use of tactics such as kettling – containing protesters behind cordons for a sustained period of time – and the controlled use of force against those who appear hostile without first holding a public debate over the future of policing public protests.

During the G20 protests the Met repeatedly attempted to "kettle" thousands of mainly peaceful demonstrators .

The technique is widely believed to have sparked angry confrontations with protesters, who complained that they were penned in for hours and subjected to baton charges.

Officers in charge of the Met's public order operations have been lobbying hard to retain the kettling tactic, which they regard as an effective method of preventing unruly protests from spreading through large areas of a city.

The select committee stops short of commenting on the death of the newspaper vendor Ian Tomlinson or the case of Nicola Fisher, who was struck across the face by a police sergeant. But the MPs say that the images and film footage of those incidents shocked the public and have the potential to undermine trust in the police. They hoped the incidents would mark the start of a widespread debate on the use of force by the police.

"The basic principle that the police must remember is that protesters are not criminals – the police's doctrine must remain focused on allowing protest to happen peacefully," said Keith Vaz, the committee chairman.

"In many ways this was a large protest which passed off remarkably well. But it is clear that concerns about the policing of the G20 protests have damaged the public's confidence in the police and that is a great shame."

He said the ability of the public and the media to monitor every single action of the police through CCTV, mobile phones and video equipment means they have to take even greater care to ensure that all their actions are justifiable.

"There must not be a repetition of this – never again must untrained officers be placed on the frontline of public protest."

The report describes the policing of the G20 protests as a "remarkably successful operation" in which more than 35,000 demonstrated in the centre of London yet with the minimum of disruption to the City: "Aside from a few high-profile incidents, the policing of the G20 protests passed without drama," say the MPs before adding that an element of luck played a part in that success.

The MPs repeat their belief that there are no circumstances in which it is acceptable for police officers not to wear their identification numbers and urge those who consciously remove them to face the strongest disciplinary action.

During the Commons inquiry, Commander Bob Broadhurst, the "gold commander" in charge of the G20 policing operation, told the MPs that there had not been any large-scale disorder in London for a number of years of the kind seen summer after summer in the 1980s and 1990s: "That means I now have a workforce of relatively young people that we draw on who are policing Sutton High Street one day and the next day called into central London."

He said there were 2,500 officers who had only two days of public order training a year and the vast majority of whom had never faced a situation as violent as the G20 protest before.

"That may also be why one or two of them, as you have seen on television, may have used inappropriate force at times ... I would probably say that was probably more fear and lack of control, whereas our experience in the past is the more we experience these things, the less quick officers are to go to the use of force because they understand more the dynamics," he said.

The MPs say the risk of relying so heavily on untrained, inexperienced officers in such a highly combustible atmosphere must never be taken again.

Their report also confirms criticisms of police communications with the media and with the protesters and question why it took the personal intervention of Broadhurst to relay the message that the press should be let out of the cordons.

The MPs' findings are published ahead of a report by Denis O'Connor, the chief inspector of constabulary, in which senior police officers will be told they must use "reasonable discretion" when containing large numbers of protesters. O'Connor was asked to carry out a national review of public order policing by the Metropolitan police commissioner in April. He is due to publish his findings this week.

O'Connor is considering whether to endorse a "human rights-based" approach to policing advocated by Sir Hugh Orde, the incoming chief of the Association of Chief Police Officers. Orde is promoting a model of policing protest developed in Northern Ireland that sees greater emphasis placed on communicating with protesters and facilitating their right to protest.

However, Orde's position, which gives protesters more freedom to roam, is considered soft by some senior Met officers.