THE Government has admitted the electrification of the Great Western Line may not be completed by the end of next year.

Network Rail is in the process of electrifying the tracks between London and Bristol Parkway, and later to Swansea, but has run into numerous problems along the way, notably around Royal Wootton Bassett.

The organisation has maintained it will still be able to have the work completed by the original target deadline of December 2016.

But answering questions in the House of Lords on Wednesday, Transport Minister Lord Ahmad conceded the date of completion may have to be pushed back.

He said: "The government is committed to delivering electrification from Paddington to Swansea.

"There are challenges which have arisen from electrification and construction and planning consents have taken longer than expected."

Earlier in the week, the Transport Secretary Patrick McLoughlin said the project was providing some big engineering difficulties and when asked if it would be completed on time, said: “I can't give you a yes or no answer."

Speaking to the BBC on Sunday, Welsh Secretary Stephen Crabb could also not confirm whether the work to Swansea would be completed by 2018.

One of the major blocks to the project has been at Royal Wootton Bassett, where Network Rail has had to build a temporary road after the initial plan to close the Skew Bridges met with strong opposition.

The Stratton Green Bridge was also set to close for several months earlier this year but it re-opened after a month after cables were found underneath the track.

A number of rail projects were put on hold after Network Rail said it had been too ambitious but the electrification remained a key priority.

When complete, it will mean a greater number of trains can run between to London and the journey time will be reduced.

A spokeswoman for Network Rail said: “Electrification will transform the railway between London and South Wales to make journeys faster, more reliable, greener and quieter for passengers.

"It will also help support economic growth across the South West.

“This upgrade is the biggest and most complex electrification scheme for more than a generation and a major investment in improving the railway for passengers.

“While work is progressing well and we’re aiming for a 2017 target for the South West, the programme is subject to change and alteration as the scope and needs of the overall project also change.”