An experienced doctor, who has questioned the official explanation for the death of weapons expert David Kelly, was dismissed by text and email while on a family holiday after he blew the whistle about alleged discrepancies in the dispensing of strong painkillers at an army base.

Dr Stephen Frost has been granted permission by a judge to take the Ministry of Defence (MoD) to an employment tribunal over the loss of his position, at a base near Blackpool, which followed his calls for police to investigate the dispensing of morphine sulphate tablets.

The doctor claimed he was not told why his contract was terminated, was given no chance to defend himself and believed he would never be allowed to work with the military again. He had suffered severe stress, anxiety and depression since being dismissed, he added.

Frost has played a key role in the campaign for a full inquest into the death of weapons expert David Kelly at the height of the Iraq dossier scandal.

Kelly was found dead in woods near his Oxfordshire home in 2003 shortly after being exposed as the source of a BBC claim that Tony Blair’s Labour government had “sexed up” a dossier that helped make the case for war in Iraq. The Hutton report concluded that Kelly, a member of a UN team sent to Iraq to search for weapons of mass destruction, had committed suicide. Frost is among doctors who continue to doubt that conclusion.

David Kelly leaves parliament in 2003 after giving evidence to the Commons select committee. Photograph: Johnny Green/PA

At a preliminary hearing earlier this month, the MoD tried to have Frost’s claim struck out, arguing that he could not officially be regarded as a “worker” for the ministry despite the fact that he had worked almost exclusively for the armed services for almost 20 years through agencies.

The MoD also argued he could not be treated as a whistleblower because he had not originally stipulated this was a basis of his case – even though the word “whistleblower” appears on his initial claim form.

But a judge ruled Frost’s claim of unfair dismissal should be heard by a full employment tribunal in the summer, a case likely to be embarrassing for the MoD.

Frost, from north Wales, told the Guardian: “It is a great relief that the judge allowed my claim to proceed. I have dedicated much of my life to working as a doctor for HM armed forces and I took my job of treating sick and injured military personnel very seriously. My summary dismissal came as a great shock to me and has seriously affected my health and my family life.”

Frost’s solicitor, Shah Qureshi, said: “Dr Frost believes he was summarily dismissed because he shone a spotlight on potential criminality at a military barracks. Other members of staff involved continue to work for the MoD while my client has lost his livelihood. To this day it is unclear as to whether the matter was ever referred to the police.”

Qureshi, head of the employment team at Bindmans LLP, said he was greatly concerned that the ministry tried to get the claim struck out on a technicality. “It is of immense public importance that whistleblowers enjoy maximum protection before the law.”

Frost was engaged to work as a civilian doctor at Weeton barracks, near Blackpool, in July 2013 through a private healthcare recruitment group. His contract was due to last until December that year.

According to Frost, on 6 August he became aware of a dispensing discrepancy involving morphine sulphate tablets that occurred almost two weeks before he started working at the camp’s medical centre. He said tablets six times the strength of those that should have been dispensed were involved.

Frost expressed his concerns to members of the practice team and later to an internal investigating team and asked for the police to be informed.

On 6 September, while on holiday, Frost’s posting was terminated by text and email and he was told not to return to work on the following Monday. He said no explanation was given.

At the preliminary hearing, Judge Rebecca Howard said: “There is clear reference in the claim form to whistleblowing. The basis of the claim is that, following Dr Frost’s participation in the investigation into incorrect dosage and dispensation of morphine, he was summarily dismissed and banned from working as a doctor in the military.”

A spokeswoman for Lancashire police said the force had not been involved in any investigation at Weeton.

An MoD spokesperson said: “This case is subject to legal proceedings and it would be inappropriate for us to comment.”