The Dáil Public Accounts Committee is expected to press ahead with plans to compel a number of individuals to appear before it next month as part of its investigation into a highly controversial €4 million fund which was used, in part, to finance foreign travel for public servants and trade union officials.

Former Siptu official Matt Merrigan told the committee in a letter earlier this month that he wanted to appeal a direction that both he and a former member of the union's national executive , Jack Kelly, give evidence before it.

A retired health service official, Alan Smith also wrote to the committee this month seeking details of any appeals mechanism against the decision to compel him to attend.

Siptu yesterday said it would not be funding any challenge to the decision of the committee to compel Mr Merrigan and Mr Kelly to appear before it. However a spokesman said that no financial assistance had been sought from it in relation to any challenge.

The committee wants to inquire about the operation of a bank account – described in the Oireachtas as a slush fund – which was used to pay for foreign travel by civil and public servants as well as union officials.

A report by the Comptroller and Auditor General found that more than €4 million in funding from a variety of State bodies, mainly in the health sector, was paid into an account known as the Siptu national health and local authority levy fund.

Siptu corporately denied any knowledge of the account.

Mr Merrigan told the committee in a letter that as the HSE had made a complaint to the gardaí, the matter was sub judice.

“By appearing before the committee, my constitutional rights are infringed.”

“By implication, Mr Kelly’s rights are also affected as the scope of the investigation is so intertwined that it is invidious to expect Mr Kelly to appear in my absence,” he said.

The committee discussed the letters from Mr Merrigan and Mr Smith at a hearing yesterday.