A criminal justice expert has quit the Home Office’s drug advisory panel, claiming political interference in the appointment process is undermining its independence.

Prof Alex Stevens, a senior member of the Advisory Council on the Misuse of Drugs (ACMD), resigned over the alleged “political vetting” of panel members by the government.

The resignation comes a few months after the crime minister Victoria Atkins vetoed the appointment of Niamh Eastwood, the executive director of the drugs charity Release, after government vetting found she had previously criticised the Home Office and called for drug policy reform.

Stevens said he knew of at least one other person who has been barred from serving on the council after government vetting, amid growing calls for a fundamentally new approach to drug policy.

“I have resigned because of my concerns over the political vetting of potential members of the ACMD,” he said.

“These were raised at a meeting in April where I asked for the minister to provide information on how many people had been excluded from serving on the panel. I also asked for further information on what the checking process consists of.”

Stevens, a professor in criminal justice at the University of Kent, said the information was not provided and there was no assurance it would not happen again. He criticised the opaque vetting process, with candidates not told how they were going to be checked.

“The political vetting fundamentally undermines the independence of the council,” Stevens added. “It is supposed to be protected by the working protocol between the home secretary and the ACMD. This does not seem compatible if ministers exclude those who disagree with them.”

It emerged in June that Eastwood had been blocked from serving on the ACMD by Atkins.

Although her expertise was recognised, previous tweets critical of government policy were highlighted during the vetting. Eastwood has repeatedly called for legal alternatives to the criminalisation of drug users and the introduction of drug consumption rooms.

The Guardian is in contact with two other people who have claimed they were blocked from serving on the ACMD after initially being recommended.

The working protocol between the home secretary and the ACMD states: “The ACMD and ministers are committed to ensuring that the best evidence-based advice is available to government on drug misuse, working together with the common purpose of reducing drug-related harms in the UK.

“In doing so, ministers acknowledge the independence of the ACMD and its statutory duties.”

However, the government has been under pressure to adopt an evidence-based approach to drug policy. Drug-related deaths rose to a record 4,359 last year from 1,496 in 2012 and there has been a greater focus on abstinence-based support amid sustained cuts to treatment budgets.

Stevens said the government had ignored the advice of the ACMD on how to reduce the deaths despite accepting a number of recommendations in 2017, eight months after the report he co-authored was published.

His analysis of government figures showed a 27% reduction in spending on drug treatment services for adults since 2015-16.

“The government accepted the recommendation to maintain investment in opioid-substitute therapy, but it has seen substantial cuts,” Stevens said.

“But I haven’t resigned because ministers ignore advice, that is their prerogative, but because the ACMD is no longer the independent body it was when I joined it. That means I can no longer be part of the council.”

Six government drug advisers resigned in protest after Prof David Nutt was famously forced to step down as chair of the ACMD in 2009 after accusing ministers of “devaluing and distorting” evidence during the reclassification of cannabis as a class B drug, against the advice of the council.

A government spokesperson said: “Ministers are responsible for appointing members to the boards of public bodies and do so in line with the governance code for public appointments.

“The names of candidates are submitted to ministers following assessment by an independent advisory assessment panel. It is then for ministers to determine merit and make the final appointment.

“It is important that candidates who are considered for these roles undergo appropriate checks to ensure they are suitable to hold these vital public positions”.