TRAINS are being delayed this week down as 10,000 tonnes of stone are used for repairs on the Chiltern line.

The service through Oxford to London Marylebone will take four minutes longer as Network Rail found heavy rain caused the embankment to shift.

The 'slight movement' on the stretch close to Bicester was found during routine inspection as is expected to have been caused by heavy rainfall after a hot, dry summer.

It has impacted 180-metres of track south of Bicester which has to be dug out and replaced with the 10,000 tonnes of stone and material this week.

It is expected to be complete by the weekend and as a result a temporary speed restriction is in place for trains - delaying Chiltern Railway journeys in and out of London by four minutes.

Network Rail chief operating officer, for the London North Western route, said: "These repairs are vital to help keep the railway through Bicester open and safe for passenger and freight trains.

"They have been carefully planned to minimise disruption.

"We will complete this work as quickly and safely as possible."

Chiltern Railways customer services director Alan Riley said: "I’d like to thank our customers for their patience whilst this work is taking place."