Six African countries are investing heavily in the latest surveillance technology to spy on activists, business competitors, journalists, and other governments, a new report says.

The Institute of Development Studies, which published the report, identified Nigeria as the biggest spender, with more than $127m (£92m) invested in surveillance-related activities and equipment in 2017.

Egypt, Kenya, Senegal, South Africa, and Sudan have also made significant investments on surveillance technology, the report said.

Internet signal interception, citizens surveillance, and internet eavesdropping often happen despite laws granting the right to privacy of communication and correspondence, it added.

"Privacy rights in Africa are very well guaranteed in most countries," Tony Roberts, one of the co-authors of the study, told BBC Focus on Africa radio's Bola Mosuro.

"However, using this surveillance technology, governments are violating those rights," he added.

National security and economic interests are cited as the most frequent justifications used by the governments to stretch their surveillance power, often in breach of the rights to privacy of private citizens and civil society organisations.

Egypt is named as one of the countries with the weakest privacy protection laws. Without an independent oversight body, the state is the only "judge, jury and regulator" says the report.

"To get governments to value and respect the legislation that does exist. It's important that the public are aware of the rights that they have," Mr Roberts said.