Drivers using a key tunnel will have to endure several more weeks of delays, it has been revealed.

A lane was closed in the Roundhill Tunnel, at Folkestone, on April 10 for safety reasons after a barrier was found to be damaged.

The move – which also includes a 40mph speed limit - has caused traffic holdups on the busy route along the A20, heading towards the M20 London-bound.

And work to solve the problem will still take weeks, highway officials warn, as specialist material is still due to arrive.

A National Highways spokesman said: “A specialist supplier has been appointed to provide, install and complete the parapet barrier repair.

“It takes a while to mobilise the right people with the right design and materials to site to do the job properly and keep road users safe.

“We expect the work to start this week and may take several weeks to complete.

“The lane closure, 40mph speed limit and free recovery service shall remain in place until the works have been completed to protect both our colleagues making the repair and our customers until the parapet has been properly repaired.”

Questions in recent weeks had been raised as to why workers had not been seen on the site.

The department explained that it was simply because work had not been able to be started yet.

The damaged parapet barrier at the tunnel viaduct has a large dent and that was found on April 13 during a routine patrol by workers.

This was 15 metres after the tunnel and it was not confirmed exactly what caused the damage.

The lane had to be immediately sealed off to make sure no vehicles go off the road.

London-bound diversions were put be in place via the A268 and A259.

The Roundhill Tunnel route is the only direct way from the Port of Dover to Ashford and Maidstone.