After 50 years of repressive rule by the same family, the people of Togo rebelled. More than 100,000 protesters filled the streets of the small West African nation this month.

The regime responded with a strong-arm tactic that has become increasingly popular among the world's autocracies: it shut down the Internet, making it almost impossible for its opponents to use social media to organize.

On Sunday, for a sixth consecutive day, the shutdown was still in effect. The Togolese people had no access to Facebook, WhatsApp, or any other Internet services on their mobile phones – the main way in which Africans gain access to the Internet – although there were reports late on Sunday night that service was finally being restored.

Since the beginning of last year, African governments have shut down the Internet at least 18 times. In some cases, including Ethiopia and the anglophone regions of Cameroon, the Internet has been shut down for months, inflicting a huge cost on the economy.

Worldwide, the number of shutdowns is increasing dramatically. There have been 62 shutdowns of the Internet this year – mostly in Asia and Africa – compared with 55 in all of last year and less than 20 in the previous year, according to a database compiled by Access Now, a digital-rights organization.

The shutdowns are often imposed during elections, protests or other crises. Regimes are worried that social media has become an organizing tool for protesters, so they issue orders to mobile-phone providers to shut down access. In many cases, the government itself is a shareholder in the leading telecommunications companies, so the shutdowns are easy to impose.

In Africa, mobile Internet services have been widely hailed as a transformative tool, strengthening democracies, boosting health and education, and helping farmers and traders to gain valuable information and market opportunities that they never had before. But those gains are threatened by the growing use of Internet shutdowns to control dissent and crush protests.

Human-rights groups have criticized the latest shutdown in Togo. "This shows how far the authorities are willing to go to muzzle anti-government criticism," said a statement by François Patuel, a researcher at Amnesty International. "Shutting down Internet services is an unjustified attack on Internet freedom and freedom of expression in Togo."

But the government was unperturbed. "I'm not a big consumer of the Internet," government spokesman Gilbert Bawara told the Voice of America radio service. "The safety of our citizens is more important."

Togo has been ruled by the same family for almost all of its 57 years of independence. Gnassingbé Eyadéma seized power in a military coup in 1967 and dominated the country for the next 38 years, becoming Africa's longest-ruling dictator by the time of his death. His son, Faure Gnassingbé, took over the presidency in 2005 when his father died.

Last week, protesters took to the streets of Togo to demand a two-term limit for the president and other reforms, but police dispersed the protests with tear gas and violence. In earlier protests in August, two people were killed and 13 injured when the police fired on demonstrators.

Estimates by Access Now suggest that the Internet shutdown has inflicted at least $300,000 (U.S.) in daily costs to the Togolese economy – a substantial amount in a small country where most people earn less than $2 per day.

Some citizens said they were forced to travel to Togo's border with neighbouring Ghana to get access to the Internet.

Other African countries with shutdowns in the past two years have included Ethiopia, Gabon, Gambia, Democratic Republic of the Congo, Uganda, Chad, Morocco, Egypt, Algeria, Libya and Mali.

The most prolonged shutdown was in the English-speaking regions of western Cameroon, where protests had erupted this year against the French-speaking government. The Cameroon shutdown lasted for 93 days, sparking a wave of international criticism.

Cameroon's elderly dictator, Paul Biya, has ruled the country for the past 35 years. His regime has denounced the use of social media as "dangerous" and "a new form of terrorism."

The Speaker of Cameroon's parliament, Cavayé Yéguié Djibril, says social media has become a "social pandemic." He has complained that the users of social media "do not have a sense of etiquette and decorum."