Social Protection Minister Regina Doherty could be forced to repay the State almost €16,000 that she received in a special allowance over the past year, according to the Labour Party.

Ms Doherty, who was promoted to Social Protection Minister this week, received €15,829 for her work at the Cabinet table as Government Chief Whip.

Traditionally, the chief whip role was treated as a 'Super Junior' ministry, meaning the office holder is entitled to attend Cabinet but does not have voting rights. However, after the general election, Paul Kehoe and Finian McGrath filled the two super junior roles allowed under law.

Rather than change legislation to create a third position, the Department of Public Expenditure devised a new 'Chief Whip Allowance' which is paid by the Oireachtas at the same rate as a super junior minister.

However, it now appears it overlooked a section of legislation which states that a whip's allowances may not be paid to any Minister of State who sits at Cabinet.

The revelation has the potential to block new Chief Whip Joe McHugh from receiving the top-up payment and comes amid a determination from Opposition parities to stop a similar pay boost for demoted minister Mary Mitchell O'Connor.

Ms Mitchell O'Connor was dropped as Jobs Minister but Leo Varadkar gave her a 'soft landing' as a third super junior minister, taking responsibility for higher education. Public Expenditure Minister Paschal Donohoe has admitted that legislative change will be needed to create the position.

Two senior counsel have now concluded that the payments made to Ms Doherty were unlawful, as has former Public Expenditure Minister Brendan Howlin.

No position of Government whip exists in law but the Department has interpreted the job as Fine Gael Whip.

All other party whips also get an allowances ranging from €5,760 to €18,240, depending on their party size.

Mr McHugh would have expected to be entitled to a TD salary of €89,965, a Minister of State salary of €34,474 and the special whip allowance, which has now risen to €16,288. This brings the total for the position to over €140,000.

Mr Howlin said that in rushing to create jobs for Fine Gael TDs, Taoiseach Leo Varadkar has "overstepped the mark by some distance".

"It is clear from the legislation that the allowance paid to the Chief Whip over the last year was unlawful.

"The legislation makes clear that no allowance for responsibilities as a party whip can be paid to any serving Minister of State, and the payments that have been made must now be returned to the State," the Labour Party leader said.

"Leo Varadkar has shown great enthusiasm for chasing overpayments paid to those on social welfare. I presume he will chase down this overpayment with the same vigour and determination."

Mr McHugh said: "The allowance for the Chief Whip is covered under 1998 legislation. All party whips in Dail Eireann receive an allowance depending on the size of the political grouping.

"The allowances to all whips are overseen by the Oireachtas, not Government.

"The provision of that allowance and all allowances to all party whips is fully in accordance with the legislation."

A Department of Public Expenditure and Reform spokesman claimed a new allowance was not created for Ms Doherty when she became Chief Whip.

"The provision of the allowance was fully in accordance with the legislation," he added.

The spokesman did not address the section of the Act which prohibits ministers of State from receiving allowances.

Ms Doherty was not available for comment.

Sunday Independent