BUSES will replace trains on most of the services between Severn Tunnel Junction and Bristol for five weeks later this year.

The closure of the 130-year-old tunnel between September 12 and October 21 is part of the works to electrify the main south Wales to London route.

It will affect the majority of passengers who travel into and out of South Wales including those to and from London, Portsmouth Harbour and south-west England.

London trains will be diverted via Chepstow, Lydney and Gloucester extending journey times by up to 35 minutes and a there will a reduced frequency of services.

Rail replacement buses will be in operation for all other services.

Network Rail, which is carrying out the work, says it is critical milestone for the project to modernise the railway.