DAKAR, Senegal – Nigeria blocked Twitter after the social media site deleted a tweet from President Muhammadu Buhari threatening secessionist groups in the south-east of the country responsible for attacks on government offices.

The government blocked Twitter, which is used by millions of Nigerians, on Friday evening after a government official described the microblogging platform’s presence in Nigeria as “very, very suspicious”.

The Ministry of Information published the announcement of the blocking of Twitter – on Twitter.

Twitter users in Nigeria have expressed outrage over the blocking of one of the main channels that their government must criticize and try to hold to account. Many have circumvented the suspension by using virtual private networks to access the service, which begs the question of how effective the ban will be.

In the tweet deleted from Twitter on Wednesday, Buhari linked the civil war in Nigeria decades ago and attacks on offices of the National Electoral Commission by arsonists and armed men.

Most of the attacks took place in the southeast, which declared itself the Republic of Biafra in the 1960s and waged a devastating civil war. Mr Buhari, who has 4.1 million Twitter followers, was a commander on the side of the Nigerian government during the war.

“Many of those who misbehave today are too young to be aware of the destruction and loss of life during the Nigerian civil war,” he wrote in the now-deleted post. Those who “went through the war will treat it in the language they understand”.

Some saw his words as a threat of genocide against the Igbo ethnic group who form the majority in southeastern Nigeria. Twitter said the tweet violated its “Abusive Conduct” policy.

Mr Buhari took office in 2015 during the country’s first peaceful change of power between two parties, but he previously ruled Nigeria as a young general in the 1980s after taking power in a coup. Since gaining independence in 1960, Nigeria has gone through many decades of repressive military rule.

Nigerian Twitter users have played a paramount role in trying to hold their government accountable. The platform was one of the main forms of communication and outreach for protesters in EndSARS, a youth-driven movement that began with calls for the abolition of an abusive police unit and resulted in much broader calls for better governance in West Africa’s largest democracy.

At a press conference after Mr Buhari’s tweet was deleted, Information Secretary Lai Mohammed compared Twitter’s actions in Nigeria with those the company took following the January riot in the U.S. Capitol, including the suspension of the former president’s account Donald J. Trump.

“When people burned down police stations and killed police officers during EndSARS in Nigeria, Twitter was about the right to protest,” he said. “But when something similar happened at the Capitol, it turned into a riot.”

The reason for the blocking of Twitter, Mohammed said later, was “the continued use of the platform for activities that can undermine Nigeria’s corporate existence”.

In April, Twitter announced that it was opening its first Africa office in Ghana because the country was “a supporter of free speech, online freedom” and an open internet. Some analysts considered the move to be a snub for Nigeria, which is home to a thriving tech industry.

Internet or social media shutdowns are increasingly used by governments around the world, especially during election periods. Countries that have censored Twitter include China and Iran.

According to tests by Reuters in Lagos and Abuja, Twitter worked for some cellular operators and not for others on Saturday.

Facebook and WhatsApp are the social networks used by most Nigerians, but the country’s intellectuals, activists and journalists tend to be attracted to Twitter – and many have been able to continue tweeting after the ban.

“Thank God for VPN” was a trend on Twitter in Nigeria on Saturday, with many Nigerians coming on the platform to comment that Africa’s largest democracy was showing worrying signs of dictatorship in the suppression of freedom of expression.

“The suspension of Twitter in Nigeria is just another way of showing that people’s rights are not an issue,” said Osai Ojigho, Amnesty International’s country director in Nigeria, in a tweet. “That is a dangerous precedent.”

“We must resist any attempt at dictatorship,” wrote Editi Effiong, a journalist who covered EndSARS.

“The final step in a failing government is always to silence anyone who indicates it is failing,” wrote Mark Essien, a Nigerian entrepreneur and software developer.

Even some government officials continued to tweet.

“You didn’t get the memo!” A Nigerian Twitter user tweeted at Sharon Ikeazor, Minister of State for the Environment, after posting a tweet on Saturday morning about a plastic pollution event.

“Which VPN do you use?” Asked another.