WORK on the M74 extension has been blamed for causing damage to a Glasgow Subway tunnel and sparking travel chaos.

WORK on the M74 extension has been blamed for causing damage to a Glasgow Subway tunnel and sparking travel chaos.

The rail service was out of action for around 12 hours yesterday after engineers discovered damage in the tunnel wall between West Street and Bridge Street stations.

It is believed the damage included plaster which had fallen on rails.

The piling work on the £700million road project was halted immediately the problem was brought to light.

An investigation is under way into how the damage was caused and work on the new road in that area has been temporarily halted.

Shuttle buses were arranged to take passengers to and from Shields road to St Enoch station.

The loss of business on the subway plus the repairs to the damaged tunnel could run into tens of thousands of pounds.

Earlier this week work started on the foundations just yards from where the damage was found.

The piling is preparatory work for the piers which will be built to carry the new stretch of motorway over the main rail line at Eglinton Street.

A Strathclyde Partnership for Transport source said: "This impacted on our services for most of the day yesterday.

"It caused a severe problem for us."

An SPT spokesman said services had resumed in time for yesterday's evening rush hour, though with less frequency than normal.

He added: "Services on the Glasgow Subway have been restored following earlier technical problems.

"Outer and Inner Circle service were affected by unforeseen technical difficulties in a tunnel.

"We apologise for the disruption.

"Specialist engineers are still carrying out investigations."

Services were operating normally today.