CAPE TOWN (Reuters) - Nigeria said on Wednesday it would boycott an Africa economic summit in Cape Town, intensifying a diplomatic row after a series of deadly attacks on foreigners in South African cities.

South African President Cyril Ramaphosa attends the opening day of the International Labour Organization's annual labour conference in Geneva, Switzerland June 10, 2019. REUTERS/Denis Balibouse/File Photo

The withdrawal of Nigerian Vice President Yemi Osinbajo from the World Economic Forum gathering has cast a cloud over initiatives to boost intra-African trade. He was scheduled to address a panel on universal energy access on Thursday.

The rioting has killed at least five people in Johannesburg and Pretoria in recent days, and on Wednesday South African companies MTN and Shoprite closed stores in Nigeria after retaliatory attacks on their premises.

South African President Cyril Ramaphosa, on a charm offensive to attract $100 billion of new investment, tried to limit fallout from the violence, which has rekindled memories of previous deadly attacks on foreigners that also led to reprisals on South African businesses abroad.

Police have made almost 300 arrests, while people across the continent have protested and voiced their anger on social media.