Transport Malta will be carrying out repairs and maintenance work on the north-bound Regional Road tunnel (towards Paceville) tonight.
The tunnel was closed for some time early yesterday after stonework fell off the ceiling, fortunately injuring no one.
Transport Malta said works start at 9pm and continue in subsequent nights.
One lane will be kept open for as long as possible but, for safety reasons there will be periods when the tunnel will have to be closed completely, TM said.
Drivers were therefore urged to seek alternative routes.