South Africa and Nigeria agreed to expand the continent’s deepest trade relationship.

The two nations signed dozens of accords Thursday that will enable South Africa to leverage the recently agreed African Continental Free Trade Agreement to tap West African markets. They’ll also boost Nigeria’s efforts to diversify its economy, which relies on oil to generate two-thirds of government revenue and more than 90% of export income.

“We have identified key sectors for investment to boost economic growth and development,” South African President Cyril Ramaphosa said at a joint briefing with Nigerian President Muhammadu Buhari in the capital, Pretoria. “These sectors include roads, rail infrastructure, mining, manufacturing and agro-processing.”

Nigeria is South Africa’s largest trading partner on the continent, with trade flows estimated at $4.48 billion last year. Only 9% of Nigeria’s total trade is intra-African, and almost half of that is with South Africa, according to data from the Stellenbosch-based Trade Law Centre.

Ramaphosa also expressed his remorse over anti-immigrant violence last month that strained relations between the two nations.

“We have expressed our deep regret at the events of the past few weeks that manifested themselves through attacks that were directed at foreign nationals and our condemnation of all forms of intolerance and acts of violence remains very, very firm,” Ramaphosa said.

Nigeria recalled its high commissioner and evacuated some of its citizens last month after a spate of attacks in South Africa left at least 12 people dead, two of them foreigners. Protests in Nigeria over the violence targeted South African companies including mobile-phone giant MTN Group Ltd. and grocer Shoprite Holdings Ltd.

South Africa has seen sporadic attacks on migrants, including Nigerians and Sudanese, souring the government’s relationship with its regional counterparts. The worst of these occurred in 2008 when about 60 people were killed and more than 50,000 forced from their homes. Another seven people died in similar attacks in 2015.