Japanese contractors NKK and Itochu Corporation have proposed building a tunnel, part of a $5bn combined bridge and tunnel scheme, across Manila Bay in the Philippines.

The undersea road link would connect the country’s two leading industry centres on the main Philippine island of Luzon.

Felicito Payumo, chairman of the Subic Bay Metropolitan Authority (SBMA), confirmed that the two companies have submitted plans for the scheme.

NKK, Japan’s second largest steel company, has already launched a feasibility study for the project dubbed the Trans Manila Bay Crossing.

Plans call for the construction of a 15km long tunnel linking Corregidor via Caballo island to Naic in the southern Luzon province of Cavite. A 6 km suspension bridge would link the tunnel portal on Corregidor to the coastal town of Mariveles in Bataan province.

The project would help improve transport links between two former US military bases, Clark air base and Subic Bay naval station, that have been transformed into the Philippines main manufacturing areas.