Dangote Cement said on Wednesday it planned to start exports from its Congo Republic plants to neighbouring States after its Nigerian exports fell 41% in 2019 when Nigeria's government closed its borders.

Nigeria shut its land border in August to curb the smuggling of rice to neighbouring states where it sells for more and an illegal arms trade. The closure has also hurt other Nigerian businesses, including cement exports, and stoked inflation.

Joseph Makoju, Dangote's outgoing chief executive, said the border closure led exports to drop to 500 000 t in 2019 from 700 000 t in both 2018 and 2017. He said the company had exported to West and Central Africa from Nigeria.

Makoju said total production volumes last year were flat at 14.1-million tonnes. Higher discounts, marketing and haulage cost caused core profit to fall 9.1%, while margins slid 59.2%, he said.

In February, Dangote Cement appointed ex-head of Lafarge Africa Michel Puchercos as its new chief executive, Makoju said.

"We undoubtedly faced several challenges last year," Makoju told an analyst call. "We are very optimistic about the market in 2020 and we expect to see some increase especially for infrastructure project."

Dangote now plans to commence export of clinker, the main raw material to make cement, from Congo in 2020 and promote its Nigerian production more heavily to support growth.

The company said it planned to commence a share buy-back programme this year once it obtained regulatory approval and said it was actively considering a London listing with its long-delayed London IPO still "under review".

Share price for Lagos-listed Dangote Cement, Nigeria's biggest listed company, was quoted at 170 naira on Wednesday, a 41% drop from its peak of 286 naira two years ago.

Shares across Nigeria's stock market has tumbled in the last two years. The oil-reliant economy has been stuck with low growth since it emerged from a 2016 recession.