The opening of a new subway at King's Cross tube station promises to relieve peak time congestion of passengers.

The subway, which links the south side of Euston Road and the Underground ticket hall, will be opened on Monday, Transport for London (TfL) said.

Scores of passengers have currently to squeeze through a smaller subway, locally dubbed the "Khyber Pass". The real Khyber Pass, winding through mountains between India and Pakistan, is notorious for robberies, road accidents and warfare.

The new subway is part of a project to renew King's Cross tube station, to be completed by 2006.

From September Thameslink will suspend its through services at King's Cross while their new station is built at St Pancras. TfL expect more people will then pass through King's Cross tube station.

Thameslink services from the north will terminate at St Pancras while services from the south will terminate at Kings Cross Thameslink in Pentonville Road. Passengers who want to travel through London will have to walk between the two stations.

To cope with the increased traffic, the new subway is being brought into service early with temporary finishes. It will separate pedestrians crossing Euston Road to the mainline station from tube passengers on the Circle, Metropolitan and Hammersmith & City lines.

Meanwhile, the old subway will remain open, with only one entrance on the south side of Euston Road in use.

Mike Crabtree, London Underground's King's Cross Project Sponsor said: "Works on the new Thameslink station will begin in September and continue until May 2005. During that time passengers may find it more convenient to avoid interchanging between Underground lines at King's Cross."