New trains on the Glasgow Subway will be the first in the UK to run with no staff on board, it was revealed on Wednesday.

Operator Strathclyde Partnership for Transport confirmed that the new fleet will have no staff after previously announcing that the trains would be driverless.

Staff will be kept on busiest trains, which will also be fitted with CCTV for the first time.

The initiative is part of a £288 million overhaul of the Subway system.

Test tracks near Ibrox Stadium will be the first to witness the trials of the new trains by the end of 2018 before entering service at the end of 2020.

They will initially operate with drivers on board, with full automation expected to follow in 2021 - the system's 125th anniversary.

Charles Hoskins, SPT senior director with responsibility for the Subway, said that they do not plan to have a staff on every train.

He said: "We will always have staff in the system, but it is not our plan to have a member of staff on every train. These will be the first fully driverless trains in the UK."

Such "unattended train operation" is already in use on some underground lines in Paris, Barcelona and Copenhagen.

Pat McIlvogue, an official of the Unite union, cited busy matchdays at Ibrox as a potential flaw in SPT's plans.

He said: ""SPT's future vision involves a Subway system which is ticketless, with no counter staff, no staff on platforms and no staff on trains.

"If that is to be the case, Unite has to raise the issue of what happens when something goes wrong?

"So there are remaining health and safety issues that are being avoided. For example, does the SPT vision involve staff-less trains when the Subway is packed with fans going to Ibrox for a Rangers game?"

Mr McIlvogue also accused SPT of "continuing prevarication" over the future of drivers and said there must be no compulsory redundancies.

An SPT spokesperson said: "We are currently looking at how we might best utilise front-line staff following the introduction of the new system.

"Staff understand and accept that there will be changes to current working practices. However, safety and customer service will always remain a priority."

Tunnels and signalling on the Subway's six-mile loop are being upgraded to enable trains to run every three minutes - and up to every two minutes before and after football matches - compared to four minutes at present.

They are also expected to operate later at night and on Sundays, boosting the current 13 million annual passenger journeys.

The trains will be open-plan, with no doors between their three carriages to maximise space.

The 17 new trains, which replace 13 introduced when the Subway was last modernised in 1980, will provide space for the first time for wheelchairs.