Motorists have been urged by the police to avoid the Mriehel bypass this morning.
The police said that material on the road (possibly diesel) was causing vehicles to skid as they drove towards Marsa.
However motorists reported to timesofmalta.com that driving towards Attard was also treacherous. Eyewitnesses said diesel had been found on the Attard-bound lane of the flyover outside the Sta Venera tunnels.
Minor collisions have been reported.
Traffic was flowing in both directions at 8.45 a.m.