Rail services on one Swindon line will remain suspended for up to four weeks because of flooding, First Great Western announced today.

There are currently no trains running between Swindon and Gloucester because the Sapperton Tunnel near Kemble has had to close.

Floodwater has severely damaged some of the tunnel lining and one shaft, making it unsafe for services to run through it.

Engineers are carrying out round the clock repairs but train operator First Great Western estimates these will take around a month to complete.

It has laid on frequent buses for travellers going between Swindon and Gloucester in the meantime but journey times have increased from the usual 45 minutes by rail to one and a half hours by road.

Railtrack is carrying out the repairs and is asking passengers to be patient.

Spokesman Eryl Jones said: "The flooding has caused severe damage at the Sapperton Tunnel. Clearly it was unsafe to run trains through there so we had no option but to close it.

"It is an important link between Gloucester and Swindon and we are conscious of the inconvenience it will cause. Our engineers are working round the clock to repair it as soon as is humanly possible but we have to do a proper repair job."

The rail network has been severely disrupted because of the stormy weather and speed restrictions imposed in the wake of the Hatfield crash.

First Great Western was forced to introduce an emergency timetable with hourly services between Swindon and London.

Last night it was able to run half hourly services at peak time between 3.15pm and 6.15pm which will continue tonight and is hopeful to resume normal services soon.

But 20mph speed limits are still in place to the west of Swindon station, at Pewsey and between Swindon, Didcot and Reading.

This means trains on the Bristol to London route are running 20 minutes late and there are delays of an hour and a half on the Swansea to London route which also passes through Swindon.

This weekend there will be alterations to services to Castle Cary, Westbury and Pewsey because of line closures.

On Saturday and Sunday the line will be closed between Castle Cary and Newbury while from Monday to November 19, the line will be closed between Westbury and Newbury.

Jo Smyth from First Great Western said: "We apologise for difficulties passengers are experiencing. We are doing our very best to provide as comprehensive a service as we can in the circumstances.

"We are improving things and are hopeful they will get even better by next week."

Anyone who is planning to travel is advised to call either National Rail Enquiries on 08457 48 49 50 or visit www.nationalrail.co.uk or www.firstgreatwestern.co.uk.