The alcohol ban is being planned after Old Firm fans were warned by First Minister Nicola Sturgeon not to travel to pubs to watch the Glasgow derby match this weekend.
The Rail Maritime and Transport (RMT) Union revealed that ScotRail informed them it will bring in a full all-hours drinking ban on trains in a bid to tighten up on Covid-19 safety measures.
But they claimed the move has been put on hold after the British Transport Police called for more time to consider the resource implications.
The union said they welcomed the move to extend the current ban to daytime hours but also warned of a 'double whammy' of pressure on frontline staff who can't enforce rules on trains.
Mick Hogg, Regional Organiser for the RMT in Scotland said: "We have been told by ScotRail that there will be a full ban on alcohol on trains as a covid-19 measure. We welcome that.
"But it has to be resourced or it puts more pressure on our staff. It's a double whammy for them. They can't enforce the wearing of masks or police passengers drinking alcohol. That has been a big issue for a while. We know the BTP don't have enough staff as it is."
One conductor said that he is terrified on packed Saturday night trains.
He said: "I've seen people swapping their masks and some refuse to wear them. I'd say about a third don’t wear them. Things can quickly get out of hand. Even though we are not expected to police the rule sometimes I do ask passengers to comply. We can ask drunk passengers to leave but that can lead to confrontation.”
"Busy weekend nights haven't calmed down in recent weeks. People from Edinburgh and Glasgow have been piling on trains across to Fife to go to the pub. I've seen packed trains with the vast majority of passengers drunk."
The worker has been assaulted, sworn at and his colleagues have been spat on. After asking one rowdy group of passengers to put their masks on after a passenger sitting near them complained, the group asked for his details and said they would report him because they said ‘you’re not allowed to make us wear them’.
"Passengers know there is nothing we can do. What's the point of making it mandatory to wear masks if there's no consequences when people don't do it?We could phone the transport police but then we face massive delays while we wait for them to get here. On a busy Saturday night, that'd take about 45 minutes or more."
Alcohol is already banned on trains between the hours of 9pm and 10am. The RMT says the all-hours ban should be permanent. Mr Hogg said: "It's nuts to say that it only be in place as a covid-19 measure. Drinking should be banned on trains permanently, as it is in football grounds and shopping centres.”
A ScotRail spokesperson said: "A ban on daytime drinking on trains is something we're looking at. I can't give any more details."
Scottish Labour transport spokesperson Colin Smyth MSP welcomed the proposed alcohol ban.
He said: “Any new measures designed to keep transport staff and other passengers safe from harm are to be welcomed.
“Nonetheless, it is vital that staff are properly supported to ensure that they are able to manage this additional rule safely.
“Transport workers have kept this country moving throughout this pandemic, often under exceptionally challenging circumstances.
“We all owe it to Scotland’s transport workers to keep them safe from harm.”
British Transport Police were asked for comment.