MINISTERS have knocked back calls to secure additional trains between Glasgow and London while setting out their requirements for passenger services on the route over the next 15 years.

Announcing the start of the bidding process for the franchise covering the West Coast Main Line – the most heavily trafficked rail route in Europe – Rail Minister Theresa Villiers said she wanted to give train companies more freedom to design time-tables and improve services.

The reforms, aimed at loosening government control, will allow bidders to add or remove stops as long as they maintain the same overall level of services throughout the week, and were broadly welcomed.

But Ms Villiers faced criticism yesterday from Glasgow City Council, which had called for an extra five weekday services between Glasgow Central and London Euston stations to be specified by the Department for Transport (DfT), bringing the total in both directions to 32.

This would fill a number of gaps in the timetable, which can see passengers waiting for up to two hours for a direct service, and follows significant growth in cross-border traffic since the completion of a £9 billion upgrade to the route in 2008.

A spokesman for the council said it was "disappointed" that the DfT had not increased the service requirement. "There are gaps in the train service on the West Coast Main Line and it is not just Glasgow that is affected by this but other stations north of Preston. We note that more services may be proposed and hope that bidders recognise the need to reduce overcrowding and provide a better service at certain times of the day."

The Invitation to Tender (ITT) document published yesterday marks the start of a bidding process that will see the appointment of a company to operate passenger services between December 9 this year and 2026, when new high-speed rail services are due to commence.

The competition has pitted Virgin Trains, jointly owned by Stagecoach and Virgin and currently operating services on the cross-border route, against Aberdeen-based First Group, Dutch rail firm Abellio, and the French state rail firm SNCF together with Keolis, in which it has a majority stake.

A spokesman for the DfT emphasised that any of the bidders could submit proposals to increase train frequencies but would not be constrained beyond providing the same overall number of services. "A new flexible franchise agreement gives bidders the flexibility to vary timetables on individual days of the week to cater for changes in demand, enabling the future operator to provide better services for passengers, whilst protecting existing services by specifying a minimum number of stops at each station," the spokesman said.

An industry source told The Herald bidders would study the ITT to see what sort of services the DfT wanted. "There would be nothing to stop the DfT specifying more Glasgow-London trains if that's what they wanted. You might see bids that include those extra services but there might be a risk that it would make the bid more expensive."

Anthony Smith of rail watchdog Passenger Focus, said: "It is essential that operators work to a set of clear targets and requirements which safeguard the overall interest of passengers."