WORK has ground to a halt on a section of the new £1.4 billion road bridge over the River Forth after a routine concrete pour was botched.

The error has set back progress on the Queensferry Crossing by around a fortnight, but Transport Scotland insisted the project would still be delivered within budget.

Disaster struck on June 5 when pipes carrying concrete from sea level to an upper deck of the north tower burst.

Workers had reportedly warned bosses that the cement was too stiff and would wreck the pipes but were told to press on.

A source said: "There was a delay transferring the the concrete from the shore to the base of the tower. By the time it got there it had started to stiffen up.

"When they started to pump it up, some of the pipes exploded. It was sheer luck that no one was badly injured or killed.

"A few of the lads told them to stop the job because the concrete wasn't correct but bosses told them to press on regardless.

"They'd poured about six lorry loads of mix before they realised it wasn't working and pulled the plug. When it set it was useless - it was far too brittle."

The new bridge is set to open to traffic next year, but buses, pedestrians and cyclists will continue to use the existing Forth Road Bridge.

A spokesman for Transport Scotland said: "Some difficulties were encountered on the first concrete pour on the north tower deck last Friday, causing the pour to be stopped.

"The small quantity of concrete placed has already been removed, cleaning work is underway and we expect to be in a position to pour the concrete in this area next week.

"The project has a set budget range of £1.35 billion to £1.4bn. This remains unchanged."