Oslo - Norwegian police on Monday were continuing a probe into a crash that claimed five lives in a 7.7-kilometre long road tunnel near Sunnmore in the west of the country on Sunday, local media reported.

The head-on collision between two vehicles occurred in the undersea Eiksund Tunnel, which was opened in February 2008.

The three-lane tunnel is regarded as the world's deepest undersea tunnel and its depth reaches 287 metres below sea level. It links the mainland with several island municipalities.

The accident was reported to have taken place at the tunnel's deepest location. Other motorists tried to assist the victims but were prevented from doing so by the extreme heat from the burning vehicles. (dpa)