Passengers were left stranded on trains in searing heat for six hours and more yesterday as the rail service buckled on the hottest June day in Scotland for 20 years.

The disruption saw no trains running out of Glasgow Central’s high level due to “multiple points failures” ScotRail said were sparked by high temperatures, creating gridlock as the mercury hit over 30C.

Network Rail last night said they were working with ScotRail to get the trains moving again and did not expect it to continue into today.

On the ScotRail Twitter feed yesterday evening, passengers were advised the heat was causing problems.

The company Tweeted: "Due to the high temperatures today, all routes going in/out of Glasgow Central are severely disrupted. Please use alternative travel where possible. Really sorry if you're affected by this today.”

All services to Ayrshire were cancelled, with other routes also suffering cancellations, suspensions or delays as engineers from Network Rail worked on the problem.

The routes included Glasgow to Paisley, Shotts, Motherwell, Cathcart, Newton, Gourock and Wemyss Bay.

Last night, a spokesman for ScotRail said: "Glasgow Central is open, however, multiple points failures in the vicinity of the station mean that we are currently unable to run trains in or out of the high level station.

"Trains from the low level platforms are not affected and engineers from Network Rail are currently on site."

On the day when the temperature in Scotland peaked at a 20-year June high of 31C in Aviemore in the Highlands, and hit around 30C in Glasgow itself, staff at the station handed out bottles of water to roasting travellers.

Many passengers took to social media to vent their dismay at the chaos, with one branding the situation an “absolute joke” as the station - with a glass roof - was described as a “greenhouse” in the rising heat.

Karen Nijar said on Twitter at around 7pm: “Stranded outside Glasgow Central on a train I’ve been on for the last five hours and we’re stuck between two sets of failed points at the mercy of Network Rail.”

And Craig Dolan tweeted: "Shocking conditions in ScotRail s Glasgow Central trains. Well over 35 degrees and no information on Barrhead trains for nearly an hour.”

Two hours later, at around 7pm, he said: "Have now been here for nearly two hours. No real information from ScotRail."

Passengers were also experiencing difficulties taking replacement buses.

Marie Ford said: “So the staff at Glasgow central are telling people they can use their train ticket on the bus but the bus drivers are refusing! Get your acts together.”

Network Rail last night denied it was a weather related incident according to their “current info”.

A spokeswoman said: “Our engineers are on site working to repair the points outside Glasgow Central. We apologise to passengers affected by this and would ask people to check their journey via nationalrail.co.uk

“Currently, it looks like the faults will be repaired by start of service tomorrow.”

Late last night, ScotRail were still fielding customer complaints online.

One tweeter said, "Only in Scotland does steel melt at 25C", to which ScotRail replied: "Rails in direct sunshine can be 20 degrees hotter than air temp.”