Nigeria's government said on Friday it was suspending Twitter's operations indefinitely, two days after the social media giant deleted a tweet from President Muhammadu Buhari's account for violating its rules.
Twitter was still working in Africa's most populous country soon after Friday's statement, which triggered immediate criticism from rights groups and analysts about freedom of expression.
Nigeria's information ministry said Twitter was "suspended, indefinitely," because of "persistent use of the platform for activities that are capable of undermining Nigeria's corporate existence".
When asked about the decision, ministry special assistant Segun Adeyemi told AFP: "I can't answer technicalities... operations will be suspended indefinitely."
The ministry also announced the suspension on its own Twitter account though it gave no details on when the decision would take effect or what form the suspension would take.
"The announcement made by the Nigerian Government that they have suspended Twitter's operations in Nigeria is deeply concerning," the company said in a statement.
"We're investigating and will provide updates when we know more."
The ministry did not give details about what activities were threatening Nigeria.
But Twitter on Wednesday deleted a remark on Buhari's account for violating regulations, after he referred to the country's civil war in a warning about recent unrest in the southeast.
The 78-year-old president, a former general, referred to those "misbehaving" in recent violence in the southeast, where officials blame separatists for attacks on police and election offices.
Minister of Information Lai Mohammed on Wednesday accused Twitter of ignoring violent messages from a separatist leader and also referred to Twitter CEO Jack Dorsey's support for the #EndSARS protests last year in Nigeria against police brutality.
Friday's decision was swiftly denounced by rights groups.
"This repressive action is a clear attempt to censor dissent & stifle the civic space," Human Rights Warch researcher Anietie Ewang said on Twitter.
'Muzzling freedom of expression'
Amnesty International called for Nigeria to immediately reverse the "unlawful suspension".
"This is the height of muzzling the freedom of expression that can only happen in dictatorships," Bulama Bukarti, an analyst at the Tony Blair Institute for Global Change, said on Twitter.
"It will go down in history as one Buhari's biggest mistakes and PR disasters."
Nigeria in 2019 had announced it would tighten regulations on social media to fight fake news and disinformation, but the proposal sparked concerns over freedom of expression.
Several countries including China and Turkey have come under fire for putting restrictions on social media platforms like Twitter.
In February Twitter condemned Myanmar's move to block access to its platform as part of a crackdown on social media, days after a coup that saw Aung San Suu Kyi and other civilian leaders jailed.