Dangote told a business forum in Lagos his firm was close to sign a deal with a Moroccan firm to supply phosphate, without giving details.

He also said his planned oil refinery would have a capacity of 650,000 barrels a day, up from an initial plan of 400,000 bpd.

"We can actually build ... 30 percent cheaper than previously," Dangote said, referring to lower construction cost as a result of cheap global steel prices.

The refinery and petrochemical complex will go online around 2018, company officials have said.

He said Dangote Group was also constructing a gas pipeline beneath the sea to link Nigeria's oil-producing Delta region to West Africa.

The pipeline will be able to transport 1.5 billion standard cubit feet of gas per day, he said, without giving more details.

Dangote Group, which is active in cement, oil, food and sugar business, is also expanding into farming.