The confirmation came as Deputy First Minister John Swinney accused the UK Government of “deliberately inflaming” the dispute over pay and jobs, and condemned its lack of action as a “dereliction of duty”.
ScotRail revealed a further 264 services would not run on the days following the strikes on Tuesday and Thursday – on top of its temporary timetable, which has already halted 574 – or one third – of daily services.
It means nearly four in ten ScotRail trains will not operate on those days, making Scotland among the worst affected parts of Britain in the most widespread rail strikes for 30 years.
The Scottish Government-owned company, which is not involved in the dispute, said this was because Network Rail’s signalling centres in Edinburgh and Glasgow would not be able to operate until 7:15am, and signal boxes outside the Central Belt would not be back in action until later in the day.
That will mean significantly later first trains on some routes, such from Dundee to Aberdeen at 11:18am compared to 7:22am normally.
ScotRail is still devising a timetable for Sunday.
The news will come as a further blow to passengers who are suffering the loss of 90 per cent of ScotRail services during strikes on Tuesday, Thursday and Saturday by the Rail, Maritime and Transport union (RMT). The industrial action involves 40,000 staff at Network Rail and 13 train operators based south of the Border.
Only five ScotRail routes operated, with the last trains leaving before 6pm.
Services were restricted to the main Edinburgh-Glasgow line, a secondary route via Shotts, and Edinburgh-Bathgate and Glasgow to Lanark and Larkhall.
Lanark passengers benefited from a half-hourly service when it has been largely reduced to hourly under the temporary timetable, triggered by drivers declining voluntary overtime as part of a separate dispute.
Cross-Border operators such as LNER will also operate a reduced service on the days between the strikes, while all Caledonian Sleeper services have been cancelled until Sunday.
The companies are running only a fraction of normal trains on the strike days, with last Scotland-London services leaving around lunchtime.
ScotRail service delivery director David Simpson said: “Regrettably, the disruption caused by the RMT Network Rail strike action extends to the days following strike action as well.
"This is due to Network Rail signal boxes across Scotland’s railway opening at different times throughout the day.
“This means, for some routes, it may be later in the day before we’re able to operate services as normal.”
Mr Swinney said: “With a busy summer upon us, there needs to be more urgency from UK ministers and the Department for Transport to get this situation fixed – and fast.
"The lack of action being taken by the UK Government is a dereliction of duty.”
The Deputy First Minister sought to make a distinction between the ScotRail pay dispute, during which the Scottish Government was criticised for not becoming more closely involved, and the separate Britain-wide dispute.
At ScotRail, train drivers’ union Aslef has recommended members accept a revised 5 per cent offer, which the RMT is still discussing internally after rejecting part of the deal that requires staff to use new technology.
Mr Swinney said: “We have had our own issues in Scotland, but the difference between our approach and that of the UK Government could not be more stark.
"We have sought dialogue, compromise and agreement, whereas the UK Government has deliberately inflamed the situation, causing misery for the travelling public.”
Transport minister Jenny Gilruth said the UK Government’s approach to the Network Rail dispute “appears to be motivated by ideology rather than practicalities”.
In a letter to Grant Shapps, she said: "Scotland looks set to be one of the worst affected parts of the GB Rail network from today – I am therefore seeking an urgent undertaking from you, to that end, that as UK transport secretary you will do all that you can to seek a resolution to this dispute, as quickly as possible, for the benefit of staff and passengers alike.
“Network Rail workers in Scotland and across the GB rail network have not received a pay rise in over two years.
"I am sure you will agree that is not an acceptable or a sustainable position.”
Ms Gilruth also underlined her opposition to compulsory redundancies, although Network Rail has said they might not be necessary.
She said: “Railway staff worked on the front line during the pandemic. Now is a time to recognise those efforts, not to punish workers.”
The RMT has raised safety concerns over threatened redundancies, but Network Rail said it was seeking to modernise working practices, such as by sending multi-skilled teams to fix track faults rather than one team going out after another.
RMT general secretary Mick Lynch said: "RMT members are leading the way for all workers in this country who are sick and tired of having their pay and conditions slashed by a mixture of big business profits and Government policy.
"Now is the time to stand up and fight for every single railway worker in this dispute that we will win."
Business leaders in Scotland have warned of the financial toll taken by the strikes, with Leon Thompson, from UK Hospitality Scotland, predicting the sector was set for "in excess of £50 million of losses" this week.
Talks between the union and Network Rail are due to resume on Wednesday.
Prime Minister Boris Johnson told a meeting of the Cabinet that reforms were vital for the rail industry and passengers.
He said: "I say this to the country as a whole, we need to get ready to stay the course.
"To stay the course, because these reforms, these improvements in the way we run our railways are in the interests of the travelling public. They will help to cut costs for fare payers up and down the country."
The Prime Minister's official spokesman said: "The Prime Minister's view is it is in the long-term interest of both the country and the public to not give in to some of these demands which would stop us being able to modernise the railways."
Meantime, in a sign of further unrest, the Scottish Police Federation on Tuesday rejected a £565 pay increase offer and will consider “internal forms of action”.
Calum Steele, general secretary of the body that represents 17,500 officers up to the rank of chief inspector, said: “At their most basic level, these actions amount to the wholesale removal of the goodwill that the service requires to operate.
"Significantly, this good will and flexibility saves the police service money, and its removal will be both costly and disruptive.
"These actions are capable of being escalated, and they are capable of being sustained.”