SCOTLAND’S rail network faces being “brought to its knees” if staff are not paid more money for overtime work, union leaders have warned.

Train conductors, station staff and cleaners have threatened industrial action in the coming weeks amid an ongoing row with ScotRail management.

The Rail, Maritime and Transport union (RMT) said its 3,500 members are expected to vote for a ban on overtime and “rest day” working within the next two weeks.

The dispute comes after an agreement was struck last year to pay train drivers £300 for working on their rest days – while other staff are paid substantially less.

Michael Hogg, the RMT’s regional organiser for Scotland, warned services will grind to a halt if workers vote to push ahead with industrial action.

He said it would be “sufficient to bring ScotRail to its knees” – with services on a Sunday, which rely on staff working overtime, particularly vulnerable.

He said: “It would crucify ScotRail. ScotRail would not be able to run a service on a Sunday. The same would apply from Monday to Saturday.

“The reality of the situation is ScotRail do not have enough resources in place to run the railway. The answer from ScotRail’s perspective is to employ more staff.

“This is a situation that has not been created by the RMT. This is a situation that has been created by ScotRail.”

He described the anger among staff, who are paid between £112 and £140 for working on their rest days, as “overwhelming”.

Industry insiders told The Scotsman that the earnings gap reflected the stronger bargaining power of Aslef, the train drivers' union.

It comes as ScotRail is already struggling with overcrowding and poor timekeeping.

Recent figures showed the punctuality of services has got worse for nearly a year.

Scottish ministers are currently preparing a bid to take over the railways, with a statement on the Scottish Government’s plans due after the summer.

A public-sector bid by state-owned ferry operator CalMac is understood to be one of the favoured options, with bosses at the firm confirming their interest earlier this year.

But current operator Abellio has repeatedly said it would have "no problem competing with a public bid".

Due to the timescales around balloting for industrial action, it is not thought services during the Edinburgh Festival would be hit by the latest unrest.

But a ScotRail spokesman denied there would be any impact on passengers at all.

He said: “We can confirm that RMT has entered into a dispute with us regarding payments for rest day working.

"We are continuing to work with the trade unions and our people to try to reach a solution that benefits everyone. We do not expect this to affect services.”