Badly-needed maintenance work is due to be carried out tonight on the Regional Road between the Kappara roundabout and Tal-Qroqq tunnels, south bound.
The works will be carried out between 9pm and 4am, weather permitting.
Traffic will be diverted to Triq Reggie Miller.
From tomorrow morning, traffic will proceed on two lanes on both directions as usual, however drivers will note that the construction site close to the petrol station area has been extended, Transport Malta said.
It cautioned that this is a construction site. Drivers are to abide to the restricted speed limit of 30km/hr, follow temporary signs and respect workers on site.