Two senior trade union officials were the signatories to a bank account at the centre of a state training scheme expenses controversy, it has emerged.
Health chiefs have asked Siptu to repay 348,321 euro channelled into the fund which paid for trips to the US, Australia, Hong Kong, Brussels and the UK.
The account was set up to administer the 60 million euro skill training scheme for lower-paid workers in the health service.
But a Department of Health boss said some of the trips had little or nothing to do with upskilling those staff.
Geraldine Smith, an auditor for the Health Service Executive (HSE), said 2.4 million euro of public funding was deposited into the so-called Siptu national health and local authority levy fund.
The account at the Bank of Ireland on O'Connell Street, Dublin, was in the name of two top Siptu officials, she said.
Matt Merrigan is the union's national industrial secretary and Jack Kelly is the president of the Dublin health services branch, and a member of the union's national executive council.
The fund was used to bankroll 31 foreign trips for senior public servants, from the HSE, Department of Health and Department of Finance, between 2004 and 2009. They were referred to as study or social partnership trips.
Siptu has said the account was not authorised by the union and was seized as part of its own investigation into the controversy. A spokesman for the union said no-one has been suspended pending the outcome of the inquiry, which is expected to be completed within the next two weeks.
"Everybody related to this has been spoken to or will be spoken to as part of the investigation," he added.