Nigerian telecoms firms have blocked access to Twitter following a regulatory directive aimed at suspending the US social media giant indefinitely.
Nigeria's government said on Friday it had suspended Twitter's activities indefinitely, two days after the platform removed a tweet by President Muhammadu Buhari that threatened to punish regional secessionists in the West African country.
The country's main telecoms industry body, the Association of Licensed Telecommunication Operators of Nigeria (ALTON), confirmed the suspension.
"Based on national interest provisions ... our members have acted in compliance with the directives of the Nigerian Communications Commission," ALTON said on Saturday.
Information Minister Lai Mohammed said on Friday the government had acted because of "the persistent use of the platform for activities that are capable of undermining Nigeria's corporate existence".
He did not say what form the suspension would take.
Twitter, which could not immediately be reached to comment on Saturday, said a day earlier it was investigating its "deeply concerning" suspension by the Nigerian government.
Buhari's government, which runs Africa's largest economy, last year proposed legislation to regulate social media following protests against alleged police brutality which were galvanised by a campaign on Twitter.
The demonstrations demanding police reforms drew global attention.
Rights group Amnesty International condemned Twitter's suspension in a tweet and called on Nigerian authorities to "immediately reverse the unlawful suspension and other plans to gag the media, repress the civic space, and undermine Nigerians' human rights".
Buhari, who was Nigeria's military ruler in the 1980s, has previously been accused of cracking down on freedom of expression. His government has denied such accusations.
Gill Atkinson, the British Deputy High Commissioner to Nigeria, wrote in a tweet on Saturday that "all Nigerians have the right to freedom of speech and the responsibility not to misuse that right".
"Any action taken by government must be measured, proportionate and not suppress basic freedoms," she said.