Guinea on Tuesday signed an agreement with a consortium for the development of its giant Simandou iron ore reserve, another step towards the realisation of a project which it hopes will bring a $15 billion windfall over the 25-year lifespan.

The deal includes the construction of a 650 km railway from Guinea's mountainous forest region to the coast, and a deep sea water port, which will unlock the development of blocks 1 and 2 of the rich Simandou iron reserve.

It is expected to be minerals-rich Guinea's largest industrial mining project to date.

"This is an important step in the development of the Guinean mining sector." Mines Minister Abdoulaye Magassouba said, adding that it will help diversify the country's mining output which until now heavily depended on aluminium ore and gold.

The consortium - which includes Société Minière de Boké (SMB) and Singapore's Winning Shipping as well as Guinean government interests - won a $14 billion tender last November to develop the blocks at Simandou, the largest known deposit of its kind holding more than 2 billion tonnes of high-grade ore.

(Reporting by Saliou Samb; Writing by Bate Felix; Editing by Chizu Nomiyama)