An MP has accused the Government of a “widespread conspiracy of silence” and a “cloak of secrecy” regarding the death of police officer Yvonne Fletcher.

Speaking at a memorial for Pc Fletcher in central London on Wednesday, SNP MP Allan Dorans criticised successive governments for failing to release evidence related to the case in the 40 years since her death.

The MP accused past and present governments of “incompetence, negligence, corruption and collusion” regarding investigations into the murder of Pc Fletcher, who was shot while policing a demonstration against former Libyan leader Colonel Muammar Gaddafi in St James’s Square, central London, on April 17 1984.

Mr Dorans, who is the MP for Ayr, Carrick and Cumnock and a former Metropolitan Police detective inspector, said he had raised the matter twice at prime minister’s questions with Boris Johnson and once with Rishi Sunak, as well as in formal meetings with both men, but claimed neither politician had engaged fully on the issue.

The MP told those at the memorial he met Mr Johnson in September 2020 but the then prime minister immediately refused to open a public inquiry into her death.

Addressing attendees, he said: “My opinion is there is widespread conspiracy of silence and non-co-operation by the Government in this.”

The MP went on to say a report commissioned in 1984 into Pc Fletcher’s death by then PM Margaret Thatcher had not been made public and, instead, its findings were “hidden and concealed by successive governments”.

In November 2021, John Murray, Ms Fletcher’s colleague and friend who held her while she died, won a civil action at the High Court in London against key suspect Saleh Ibrahim Mabrouk – a senior member of the pro-Gaddafi Libyan Revolutionary Committee that ran the embassy at the time of the shooting.

Mr Justice Martin Spencer ruled Mabrouk, who denied any wrongdoing, had “clearly assisted in the commission of the shooting” and was jointly liable with the unknown gunmen.

Speaking at the memorial, Mr Dorans said: “I suspect that the information contained in the Duff report was held since 1984 under a cloak of secrecy and the evidence against Mr Mabrouk not being released in 2017 under the grounds of national security will highlight failings and will be an embarrassment to successive governments and government agencies.

“I strongly believe when this information is finally released it will reveal government incompetence, negligence, corruption and collusion.”

On Wednesday, Mr Murray launched a campaign to fundraise for a private prosecution to hold Mabrouk criminally responsible for the officer’s death.

When asked why he thinks the Government is reluctant to engage in his campaign and release information related to Pc Fletcher’s death, Mr Murray said: “The honest answer to that is I really don’t know.

“At the moment, we’ve got no dialogue with them at all, and we never have over the last 40 years.”

On Mr Sunak’s response to the campaign, Mr Murray said: “At a meeting (he) promised us a lot of help, a lot of assistance, and then a few weeks later we got a letter saying basically ‘no way’.”

Mr Murray told the PA news agency he has written to Labour leader Sir Keir Starmer in the last few months to ask for his position on the campaign but is yet to receive a response.

Nick Price, head of the CPS special crime and counter terrorism division, said: “The death of Pc Yvonne Fletcher was tragic and our thoughts remain with her family, friends and colleagues.

“Any individual has the right to bring a private prosecution under the Prosecution of Offences Act.

“In any case referred to the CPS, including cases in which the CPS is requested to intervene in a private prosecution or in a proposed extradition, a review of all relevant material available to the CPS would be conducted in accordance with our legal test.”

The Home Office has been approached for comment.