A railway bridge has closed after an inspection found it was wobbly, forcing thousands of passengers into longer journeys until at least the start of summer.

The main rail line connecting the Midlands and northern England with the south coast was closed last week at Nuneham Viaduct in Oxfordshire.

The bridge across the River Thames, a few miles south of Oxford, requires emergency repairs owing to “a lot of movement in the structure”.

Network Rail has now confirmed that the line, which links Oxford with Didcot and Reading, is expected to remain shut for another seven weeks, until at least the end of May.

Commuter passengers travelling from the Cotswolds and Oxfordshire to London will also be impacted.

The bridge had been monitored for a number of months, Network Rail said, but measures put in place to make its foundations more secure had not worked.

Apologising to passengers, Nicky Hughes, Network Rail Western’s communications director, said in a video posted to Twitter: “We’re really sorry for passengers and freight users that we’ve had to close this critical stretch of line between Didcot and Oxford.

“That’s because the bridge… is starting to move and it’s moving now to the extent that we don’t consider it safe to run trains over.

“We’ve been monitoring this bridge for a number of months now and we’ve been taking measures to try and make the foundations of the bridge more secure, but unfortunately, those measures don’t appear to be working.”

She said that “significant rainfall” in the past month had also added to the structural problems with the bridge.

“Because the structure is not safe, we cannot run passenger and freight trains over it. That’s why we’ve had to close it,” she added.

Network Rail has advised passengers to check before they travel and said a revised timetable would be in place for the duration of the line closure, with a rail replacement service and local shuttle services running.

“Those travelling between London Paddington and Oxford/North Cotswolds will need to change at Didcot Parkway for replacement bus services, adding about 40 mins to journey times,” a spokesperson for Network Rail told The Telegraph.

“Passengers travelling between the Midlands and south coast will also need to use replacement bus services between Oxford and Didcot Parkway.

“A shuttle train service is also operating between Didcot and Appleford and Culham, and between Radley and Oxford. Trains will continue to operate largely as planned between Hereford/Worcestershire and Oxford,” they added.