Train services on the main route between Glasgow and Carlisle will be delayed by a further month because of damage caused by recent flooding.

The Lamington Viaduct in South Lanarkshire, which has been closed since it was severely damaged by Storm Frank, has suffered further damage meaning it will not reopen until the first week of March, 2016.

Engineers have been working round-the-clock on the West Coast Main Line to divert the Clyde using more than 1500 tons of stone to dam part of the river and stabilise the structure.

The viaduct’s second pier was left on the brink of collapse when floodwaters scoured out much of its foundations.

Having successfully stabilised the damaged pier on Wednesday by pumping more than 300 cubic meters of fast-setting concrete into the void, engineers have now been able to conduct structural checks on sections of the viaduct it was previously too unsafe to inspect.

It was initially hoped work to reinstate the viaduct would have been completed by February 1. However, the latest inspections have shown the continued bad weather and high water levels have caused structural damage to another pier on the viaduct.

Three steel bearings, which support the bridge deck and track have been damaged and damage to the foundations is worse than previously thought, requiring more time and significantly more work to properly stabilise the structure.

Phil Verster, managing director of the ScotRail Alliance said: "The damage caused by Storm Frank to the Lamington Viaduct has been very serious.

"Our engineers have been in a race against time to get the structure stabilised and prevent it from collapsing into the Clyde. Only now that we have won that race can we really see the full extent of the damage.

"The damage from the floodwaters is significant. We have had to use hundreds of tons of rock to divert and reduce the flow rates at the piers and an extraordinary amount of concrete just to stabilise the second pier.

"Unfortunately the scale of the damage and the complex nature of the engineering challenges means that the repair is going to take longer than we initially thought.

"All of the train companies who operate services on the West Coast Main Line are working together to make sure that we keep goods and people moving.

"The temporary timetables and arrangements that have been in place for the past couple of weeks are going to have to continue.

"That is why it is so important that anyone who is travelling on this route checks their travel details before they travel. All the companies have information on their websites and have staff ready to answer any questions you might have.

"I know that the damage that Storm Frank has caused to this viaduct is impacting on a lot of people. We are doing everything we can to get the repairs done and the line reopened quickly and safely."