Holyrood ministers have been warned they face “international humiliation” if industrial disputes on the railways are not resolved by the time world leaders descend on Glasgow for the global Cop26 climate change summit.

Labour transport spokesman Neil Bibby demanded the Scottish Government step in to end trade union action, which has seen train services on Sundays massively reduced.

He claimed that industrial relations on Scotland’s railways were “at an all time low” and without ministers seeking to resolve the situation he added that “industrial action during Cop26 is likely”.

Mr Bibby added: “It would be an international humiliation for the Scottish Government. Are they really willing to stand by and let that happen?”

His comments came as he challenged the Scottish Government to restore ScotRail services to the level they were at before the coronavirus pandemic.

Holyrood debated problems on the railways as unions protested outside First Minister Nicola Sturgeon’s Bute House residence in Edinburgh.

Hitting out at reductions in rail services following the pandemic, Mr Bibby said recent proposals, announced on the same day as the co-operation agreement between the Government and the Scottish Green Party, would see 300 services a day cut.

The Labour MSP said: “Greener government is impossible with a declining rail network – children watching Thomas And Friends could tell you that.”

With the ScotRail franchise due to come under Scottish Government control, Mr Bibby added: “We believe in public ownership to make the railways better, we should have a growing rail network and a better rail network with public ownership, not a declining one.

“That is very much what it looks like is going to happen.

“We accept that timetables can change – but the overall level of service must not be diminished.”

Transport Minister Graeme Dey said ScotRail was currently running 2,000 services each week day with 551,000 seats – with this down from the 2,400 services that operated Monday to Friday in 2019, with a total of 645,000 seats.

However the minister insisted services would grow as Scotland recovers from the impact of coronavirus.

Mr Dey said: “Labour say there should be no overall service reduction. In effect they are saying that what was suitable for 2019 should be suitable for 2022.

“Do they not recognise that there have been substantial economic, societal and environmental changes since 2019, and these changes will have a material effect on the provision of railway services.

“There will be changes to working patterns, where we work and how we work which we have yet to understand what they will mean for the future.

“Therefore what we need is a level of service provision that meets the changing needs of passenger demand as Scotland comes out of Covid, but with the flexibility for beyond.”

But Tory MSP Graham Simpson said: “With Cop26 just weeks away it beggars belief that the Scottish Government is happy to preside over massive cuts to rail services, despite this being a sustainable and low carbon form of transport.

“This will do nothing to make Scotland a net zero nation.”

He told Holyrood: “We are wholly opposed to these cuts. My concern is that they will just stay when ScotRail is nationalised and things will get worse and worse.”