Leeds-based group The Forgotten Heroes said it was "disgusted" to find its savings had been plundered by fraudsters.
Disabled veteran and group founder Adam Douglas discovered more than 500 had been taken from a Lloyds TSB account.
"I couldn't believe it. I'd gone to deposit money from fundraising activities and I'd got a balance which seemed very low.
"I queried it with the bank and several direct debits had been set up to insurance companies for motor insurance.
"The bank have said that this is a scam where organised criminal gangs clone people's identities and credit cards in order to steal cars to order, then use bank accounts to charge direct debits for cover notes.
"The police have been informed and investigations are under way and we will get the money back, but I'm stunned that anyone would steal from a charity in this way."
The group had published its banking details on its website to enable donations, which is contrary to advice given by the Charity Commission.
In July, the commission advised charities which receive regular electronic payments to restrict access to account information.
It said the information should be treated on a "need to know" basis, or to those responsible for processing payments.
The commission outlined a number of guidelines aimed at helping charities to prevent fraud after working with the Serious Organised Crime Agency (SOCA).
Commission chief executive Andrew Hind said: "The commission is concerned to make sure that charities do not leave themselves vulnerable to the same kind of scams that are known to have impacted on private sector companies."
SOCA fraud expert Colin Woodcock said: "Scams cost the UK billions every year, and the criminals behind them are plausible and endlessly inventive.
"No-one, including the charity sector, should think they are immune. SOCA is attacking the problem in many ways.
"Our work with partners, particularly overseas where many of these scams originate, is helping to squeeze the routes that criminals use to target the UK.
"But there is also a huge impact to be made through increased awareness. Following some simple advice can be the key to making sure the criminals don't succeed."
The group, which provides advice and assistance to wounded service personnel, has been raising funds as part of its drive to become a registered charity.
Forgotten Heroes publicity officer Charley Downey
said: "The only place other than with us that our banking
information is available is on
our website, where it is
available for people who wish to donate.
"In this regard we're no different to any other charity. What sickens me is that in order to get our banking information the thieves would have had to go through our website, where it's clear that we're set up to provide help and support to wounded veterans and their families and carers.
"This isn't faceless crime, it is an organised gang stealing from men and women who've given their lives and health in service for our country.
"There aren't the words to describe the kind of people who would do that."