The works, to build air vents and repair walls, began in June and were expected to be completed at the end of October.

However, according to L'Essentiel, delays and further works to the tunnel in the other direction, will mean that it won’t be fully reopened until the middle of November.

Motorists are warned that the A1 motorway will be closed to traffic on September 11 and 12 from the night of September 10.

Luxembourg police will be on the look out for speeding motorists in the tunnel during the nights until the roadworks are completed.