A railway tunnel underneath the Bosphorus Strait is due to open in Turkey, thus creating a new link between the Asian and European shores of Istanbul

Japan's Prime Minister Shinzo Abe will be present at the official opening in recognition of the Bank of Japan's status as the project's principal financial backer.

City officials say the tunnel will relieve pressure on the two existing bridges, as well as ease traffic congestion and pollution.

Turkey's Prime Minister Recep Tayyip Erdogan has for years championed the undersea engineering project, conceived by an Ottoman sultan in 1860.

Work began in 2004 but archaeological excavations delayed the construction.

Japan invested $1bn of the $4bn total cost of the 0.8 mile (1.4 km) tunnel, designed to withstand earthquakes.

It is scheduled to be inaugurated at 13:00 GMT. The rail tunnel will not be fully operational after its official opening on Tuesday.