One of the capital’s busiest Underground stations is to shut for nearly three years. Blackfriars station, used by about 44,000 City workers and tourists every day, will close for works to upgrade the main line Thameslink.

Along with thousands of passengers within Central London, commuters from Brighton, Wimbledon, Gatwick and St Albans use the station to get on to the Tube network. The overground routes will remain open at the station throughout the works.

Blackfriars, next to the Thames and close to St Paul’s Cathedral, will close from March next year until late 2011. Circle and District line services will run through the station without stopping.

Yesterday’s announcement prompted concerns about commuter disruption, with the nearest Tube stations ten minutes’ walk away. There were also fears of delays to the planned works because Network Rail has been criticised for presiding over several project overruns.

In February the company was fined £14 million for causing severe disruption to Britain’s busiest railway line over the new year. The Office of Rail Regulation described the four-day overrun at Rugby, in the West Midlands, and delays to works at Liverpool Street station in London and near Glasgow, as a serious breach of its licence. Last year Network Rail was fined £2.4 million for failing to complete a resignalling scheme at Portsmouth on time.

There were indications that some businesses will move away from the City rather than put up with the disorder on the transport system. KPMG, the professional services firm, which has offices with 1,200 workers in nearby Puddle Dock, confirmed that because of the redevelopment it would leave its premises at the end of this year. A spokesman told The Times that a move had been under consideration but that the announcement of the works at Blackfriars had brought forward the decision.

While the station is shut, Network Rail will redevelop the Blackfriars station complex. Work includes lengthening platforms to accommodate longer trains, a new entrance on the south bank of the Thames and the redevelopment of the Tube station.

Once the £350 million project is completed, the new main-line station will able to deal with three times more trains and passengers than at present. It will be the first station in London to span the Thames — enabling direct access to the South Bank and attractions including Tate Modern.

The Tube station, which opened in 1870, is one of the oldest on the network. The works will form part of the £5.5 billion upgrade of the Thameslink line.

Jo de Bank, of London TravelWatch, said: “This really is a case of pain now for gain later. This is going to affect a great many passengers, but the upgrade of Thameslink must be done.”

Richard Parry, London Underground’s director of strategy and service development, said: “The redevelopment of Blackfriars Underground station is part of Network Rail works. Once the works are complete, customers will get a new upgraded station with step-free access, increased capacity and better interchange facilities between the Tube and national rail services. During this time District and Circle line services will not stop at the station and customers are advised to use nearby Temple and Mansion House stations.”

A spokeswoman for Transport for London said that commuters would adapt quickly to the changes and find alternative routes.

Thameslink and Southeastern commuters wishing to connect to the Underground will have to use Farringdon, Elephant & Castle or London Bridge stations.

Network Rail said that upgrade work at Farringdon station will not affect passengers transferring from Blackfriars.

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