The police officer who attacked Ian Tomlinson at the G20 protests will be accused of "inadvertently causing or contributing" to his death at a gross misconduct hearing, it was revealed today.

PC Simon Harwood, a member of the Metropolitan Police's Territorial Support Group, was today served with papers accusing him of responsibility for the death of Tomlinson, a 47-year-old newspaper seller.

The Crown Prosecution Service (CPS) announced Harwood would not face criminal any prosecution in July. An inquest into the death is expected to take place next year, and will be presided over by a senior judge, Peter Thornton QC.

Today the Independent Police Complaints Commission (IPCC), which launched an inquiry into Tomlinson's death following an investigation by the Guardian, said that Harwood would be accused of using force that was "not necessary, proportionate or reasonable in the circumstances".

Tomlinson was struck to the ground by Harwood as he tried to walk home through the protests near the Bank of England on 1 April last year. Harwood had concealed his face with a balaclava and concealed his badge number.

Although an internal procedure, the disciplinary hearing may be held in public, the IPCC said. A panel consisting of two senior Metropolitan police officers and a member of the public will preside over the hearing, and determine Harwood's guilt.

The decision to accuse Harwood of misconduct equivalent to manslaughter is likely to place additional pressure on Keir Starmer, the director of public prosecutions, who controversially decided the officer should not even be prosecuted for assault.

"I know how seriously the Met have taken this matter," said Deborah Glass, the IPCC commissioner for London. "Although misconduct hearings are determined on a lower burden of proof, the Met still needed to consider the same difficult issues identified by the CPS in their decision not to prosecute. To include the allegation that the officer's actions caused Mr Tomlinson's death was a tough decision and in my view is the right thing to do."

The misconduct charges lodged against Harwood include that that he struck Tomlinson on his left thigh with his baton and pushed him so he fell to the ground. The two combined are described as having "inadvertently caused or contributed to the death of Mr Tomlinson".

"From the moment the video was published to the world in April 2009, there has been an overwhelming public feeling that the officer seen to strike Ian Tomlinson should be held accountable for his actions," said Glass, explaining the delay in the complaints system.

"I am aware that, to those who are not familiar with the police misconduct system, it is difficult to understand why this process should take so long. First, we had to await a decision by the CPS about whether a criminal case would be brought. That decision was made by the CPS on 22 July 2010. Following their decision not to prosecute, we had to then await the misconduct proposals of the Metropolitan police, which we formally received and agreed earlier this month."

Glass said that, due to the "gravity and exceptional circumstances" of the Tomlinson case, she was considering whether to direct the hearing to be held in public. Interested parties - including Harwood, the Tomlinson family and 105 witnesses - are being asked their views.

Tomlinson's widow, Julia, said in a statement the disciplinary hearing was not the "genuine accountability" the family had hoped for.

"Whilst we believe that any disciplinary hearings must be held in public, we have already been badly let down by the Crown Prosecution Service and have real worries that these misconduct proceedings will lead to yet another whitewash," she said.

"We are also gravely concerned that holding hearings before the inquest takes place may prejudice its outcome and further undermine the possibility of the kind of justice that overwhelming public feeling demands."