A series of strikes were staged

ScotRail introduced its emergency timetable - which saw services cut by about 25% - in January.

The move came after some drivers refused to do overtime or work on rest days as part of a pay dispute which began with unofficial action by some central belt staff over the festive period.

Although working on rest days is voluntary, ScotRail depended on the practice to maintain its normal timetable.

The drivers' action was followed by a series of one-day strikes which brought the Scottish network to a virtual standstill.

However, further stoppages were called off following a breakthrough in talks between unions and the company at the end of March.

Drivers' union Aslef has recommended that drivers accept the offer, which it said would mean a 14% pay increase over the next year and 22% rise within 18 months.

Improved timetable

A postal ballot of union members will take place on Thursday.

However, ScotRail has warned that its services are unlikely to return to normal "for some time" even if there is a yes vote.

The company says it plans to introduce an improved timetable as soon as possible.

We will not rush into full timetable operation without first assessing the level of return to rest day working among drivers

ScotRail spokesman

But it said this would have to be "robust and reliable" and would take time to implement.

ScotRail acknowledged that there may not be a full or immediate return to rest day and overtime working by drivers.

"We will not rush into full timetable operation without first assessing the level of return to rest day working among drivers," said a spokesman.

He also said that more than 150 drivers still had to undergo courses to prepare them for the introduction of electric trains to North Clyde suburban services.

Another 100 drivers in Edinburgh and Stirling also need to learn the route for the �10m Edinburgh Crossrail service, which is set to begin in June.