The charity treats ex-service personnel who served in Iraq or Afghanistan
Care offered by the NHS to military veterans with post traumatic stress disorder is "a spit in the ocean", the head of the charity Combat Stress says.
Outgoing chief executive Commodore Toby Elliott says his charity has 9,000 registered patients but the government provides for less than half of them.
He says six community NHS mental health pilot schemes are inadequate and may end up providing patchy service.
The Department of Health says it is working hard to provide adequate care.
Currently, 300 former service personnel who served in Iraq or Afghanistan are being treated by the charity, which looks after veterans with psychological injuries.
In January this year, Britain's highest-decorated serving soldier criticised the government for failing to help ex-servicemen and women suffering mental health problems.
Lance Corporal Johnson Beharry, who was awarded the Victoria Cross, said it was "disgraceful" some veterans struggled to get treatment.
L/Cpl Beharry has spoken about his own mental health
He told the BBC the Army provided "first-class" treatment but ex-soldiers were forced to wait on the NHS.
At the time, a Department of Health spokesman said ministers were working with the Ministry of Defence on "improving information on how veterans' health needs differ from those in the population more generally".
He said a range of pilot schemes had also been implemented in the past year to "better identify and treat veterans with mental health problems and ensure continuity of care for those discharged from military service".
Figures published by the Ministry of Defence in November last year showed nearly 4,000 new cases of mental health disorder were diagnosed among armed services personnel in 2007.
They also showed personnel sent to Afghanistan or Iraq were more likely to suffer post traumatic stress.
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