Millions of Nigerian Twitter Users Blocked as Ban Takes HoldMillions of Nigerians struggled Saturday to access Twitter, a day after authorities suspended the service in response to the company's deletion of a tweet by President Muhammadu Buhari for violating its terms of service. The Twitter ban took effect Saturday morning. Millions of users in Lagos and Abuja said they were unable to access their accounts. Authorities said Friday that they had banned Twitter because it was persistently being used "for activities that are capable of undermining Nigeria’s corporate existence.” Twitter responded to the ban, saying it was "deeply concerning." 'Reverse the unlawful suspension' Many citizens and rights groups objected to the ban. Amnesty International said it was a threat to free speech and must be reversed without delay. "Amnesty International condemns the Nigerian government's suspension of Twitter in Nigeria," said Seun Bakare, a spokesperson for the organization. Bakare said Amnesty had called on Nigerian authorities "to immediately reverse the unlawful suspension and other plans to gag the media, to repress the civic space and to undermine human rights of the people. The Nigerian government has an obligation to protect and promote International human rights laws and standards." The ban mostly affected the country's largest network providers, MTN and Airtel. Some users Saturday were able to access Twitter using Wi-Fi connections. Others were avoiding the shutdown by using virtual private networks that make them appear to be using Twitter from another country. VPN providers have since Friday seen a surge in usage. Abuja resident Basil Akpakavir was among Twitter users getting around the government ban. "They are relentless in their intolerant attitude toward people that have contrary opinion to theirs," Akpakavir said. "But the truth is that we're equal to the task, as well. Whichever way they want it, we're going to give it to them. We want a Nigeria that is prosperous, that is built on the tenets of true democracy." Separatist group singled out Buhari had threatened earlier in the week to crack down on separatist group Indigenous People of Biafra (IPOB), in a manner similar to the civil war waged in 1967 when 3 million Biafrans were estimated to have died in battle against the Nigerian government. The president's tweet was criticized as a war threat to separatist groups, and Twitter deleted it. Amnesty’s Bakare said the government must be held accountable for comments capable of instigating division and violence. "It is important that government platforms, and in this particular instance the president, do not invite violence or division," Bakare said. "The government must be alive to the increased tensions in the country, given the spate of insecurity." The Nigerian government has often attempted to regulate the use of social media to reduce criticism. Late last year, the government proposed a social media regulation bill after the End SARS protests against police brutality, when social media were used by young Nigerians to mobilize and challenge what they said was bad governance.