And in the Republic of Congo, internet access was blocked, television networks switched off and the nation’s main airport closed during an election that spurred violence. Government officials were accused of using airstrikes on opposition forces.

Elsewhere on the continent, Ethiopia has shut down some social media sites and internet services after demonstrations. In Zimbabwe, after protests over the travails of daily life, officials raised prices on cellphone data, a move widely seen as an effort to curb the use of social media. Lawmakers also pushed measures to allow the police to intercept data and seize electronics like laptops and cellphones, levying charges of terrorism for misuse. The Democratic Republic of Congo has blocked social media sites and text messaging amid demonstrations over the president’s attempts to extend his tenure in office.

Freedom House, an American watchdog organization, said in its annual Freedom on the Net survey of 65 countries that 24 nations experienced restrictions on social media and communications last year, up from 15 countries the previous year. Network shutdowns occurred in 15 countries last year, more than double that in 2015, the survey found.

Mai Truong, program manager for the survey, said, “It’s a strategy that the authorities are increasingly turning to as a method of controlling both the information landscape and citizens’ ability to mobilize, in recognition of the fact that the internet has become a fundamental tool for people to realize their rights and participate meaningfully in society.”

The United Nations Human Rights Council last year condemned the practice of intentionally preventing or disrupting access to information on the internet, saying access was a fundamental human right.

Network blackouts also have economic consequences. Many residents of some regions of Africa where joblessness is soaring are increasingly using online or mobile transfers to receive money from relatives in urban areas or abroad. If the internet is shut off, users cannot use Wi-Fi to transfer cash and must pay for mobile data to go online. The cost is prohibitive for many people.