A mental health charity for military veterans is no longer able to take on new cases in England or Wales because of a funding crisis.

Combat Stress said its income has fallen from £16m to £10m in this financial year partly because of a cut in its NHS funding support, and said the decision to turn down new cases had been taken “with great sadness”.

The charity said that until 2018 it got more than £3m a year from NHS England, but that 90% of its funding now came from public donations. Combat Stress still gets more than £1m from NHS Scotland and will continue to take on new cases there and in Northern Ireland.

It had been receiving around 2,000 referrals for treatment every year. It will now send all new referrals from England and Wales to the NHS, which Combat Stress said needed to demonstrate it could deal with the increased demand.

Sue Freeth, the chief executive of Combat Stress, told the BBC: “I don’t believe the NHS can pick this up. That is why we exist.” She said 80% of veterans who came to the charity had either used the NHS and not had their needs met, or had felt unable to use NHS services.

Johnny Mercer, the veterans’ minister, said he would hold an urgent meeting about Combat Stress’s challenges.

Last September, Mercer, who is a former army captain, vowed to provide veterans with the best mental health care in the world after saying post-combat stress “ripped apart” those with whom he had served.

He said: “I have an intimate understanding of the issues. I am not going to pretend for a minute that I have all the answers – I don’t think anybody has got all the answers. But I am determined to get mental health care – whether it’s in the veterans’ community or the military community or indeed the NHS – to a place where we can offer those who have served in this country the best mental health care in the world.”

Several organisations and charities have spoken of a rise in the number of veterans killing themselves.

• In the UK and Ireland, Samaritans can be contacted on 116 123 or email jo@samaritans.org or jo@samaritans.ie. In the US, the National Suicide Prevention Lifeline is 1-800-273-8255. In Australia, the crisis support service Lifeline is 13 11 14. Other international helplines can be found at www.befrienders.org.