Having to peddle "government lies" about the safety of soldiers in Iraq led to a Ministry of Defence press officer suffering post-traumatic stress disorder, an employment tribunal will hear.

John Salisbury-Baker will claim that he suffered "intolerable stress" through having to "defend the morally indefensible" when responding to media inquiries about the ability of army vehicles such as the "Snatch" Land Rover to protect soldiers.

Mr Salisbury-Baker, 62, says he found it impossible to support the official line on deaths and injuries after seeing the suffering of soldiers' families. After 11 years of service at Imphal Barracks near York, he could no longer keep working and is taking legal action against the Ministry of Defence (MoD).

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The case takes place amid accusations over the government's attempts to claw back compensation from two injured soldiers, as well as a rising toll of casualties from improvised explosive devices in Afghanistan.

Mr Salisbury-Baker's partner, Christine Brook, said: "John is an honest, sensitive and moral person, and having to peddle government lies that soldiers in vehicles such as the Snatch Land Rovers were safe from roadside bombs made him stressed.

"He was particularly plagued by the thought that some of the bereaved families he was visiting might have previously believed their loved ones were safe, because of what he himself had said to the media.

"He felt responsible. He has been diagnosed as suffering from post-traumatic stress disorder by his doctor and is pursuing a claim for disability discrimination, on the grounds that the stress of what he was being asked to do effectively made him disabled."

Mr Salisbury-Baker will say that about 30 per cent of soldiers killed in Iraq came from the area in which he was working. Ms Brook said his job "was to visit families just hours after an officer had called to tell them the news that their loved ones were dead." He provided a "media shield" to help them deal with the press interest.

"He helped more than a dozen families through this traumatic time, whereas I believe the officers deployed to give the bad news to families only had this duty once, with the role passed on to someone else the next time," she said. "He sometimes attended funerals at the same church on more than one occasion."

Ms Brook claimed that the MoD had failed to give her partner training on how to cope with the stress of dealing with the bereaved and this had contributed to his illness.

An MoD spokesman said it would be inappropriate to comment when tribunal proceedings were pending."