THE leaders of the UK Liberal Democrats have been urged to make the party's all-male MSP group sign up to new Holyrood arrangements on maternity leave.

The Scottish LibDems are the only party who have refused to join a “pairing” system aimed at maintaining the balance of power when MSPs are on maternity and paternity leave.

The informal pairing of MPs has long been standard practice at Westminster, with MPs of different parties agreeing not to vote when one is unavoidably absent from parliament.

Although pairing has not been a regular feature of Holyrood, the absence of North East Labour MSP Jenny Marra on maternity leave has now led to a cross-party deal.

The SNP, Labour, Tory and Greens signed a pairing agreement before the summer recess aimed at protecting "parental rights” and the relative balance of seats in the chamber.

It does not apply to confidence motions, conscience votes or committee work.

But the five-strong LibDem group, all men, refused to participate.

SNP MSP Ruth Maguire has now written to UK leader Sir Vince Cable and his deputy Jo Swinson, MP for East Dunbartonshire, asking them to “correct this severe error of judgment”.

She wrote: “I wish to draw your attention to the fact that the only party that failed to sign up to the agreement was the Scottish Liberal Democrats.

“This was not simply oversight, but an active decision not to participate in an agreement that would protect the rights of new parents that can only have been made out of an intention to exploit the position of new parents for political gain.”

She said the decision by the “entirely male” group raised questions about the party’s commitment to equality and “encouraging young women and men into politics on equal terms”.

She added: "It is disappointing that only the Scottish Liberal Democrats have thus far refused to sign up.

“I urge the new Liberal Democrat leadership to use their influence and encourage Willie Rennie’s group at Holyrood to sign up to this agreement - their continued refusal would be bitterly disappointing and leave the impression that parental rights are not at the forefront of the Liberal Democrat agenda.”

A Scottish LibDem spokesman said: “We are very happy to respond to any request from the Scottish government on a case by case basis.

“But we did not consider it necessary to be required to sign a written agreement with the Scottish government.”