The nationwide mobile internet blackout started on Tuesday. Ethiopia's internet service is entirely in the hands of Ethio Telecom, the state-owned telecom provider. It's the third time within a year that Ethio Telecom has taken such action.

According to Ethiopian blogger Danel Birhane, the blackout has left very few companies and organizations online - only the ones that have alternative means of connectivity such as satellite communication. The capital, Addis Ababa, is home to the African Union and the UN's Economic Commission for Africa headquarters.

Officials at both institutions said their internet was cut off but later returned. However, on Thursday afternoon most Ethiopians were still unable to communicate. "It's not only mobile internet services that have been cut off but even landline. I cannot even monitor my own website, social media platforms or check emails; it's really complicated," Birhane said in an interview with DW.

According to internet giant Google, preliminary data suggested that there was indeed a big drop in Ethiopian internet traffic to its services from Wednesday afternoon. Birhane said the cut-off was unnecessary and violated the digital rights of Ethiopians. "Internet cafes have been closed. Sometimes I feel like we are 15 years back as a country. Something needs to be done," he said.

Ethiopia has been censoring its internet for more than a decade, and social media sites like Facebook and Twitter have been blocked since unrest last year. Just last month, an Ethiopian court sentenced opposition politician Yonatan Tesfaye to six and a half years in prison for allegedly criticizing the government through his Facebook posts.

Ethiopia, which has one of the lowest internet and mobile connectivity rates in the world, was among the first countries to censor the internet to curtail political protests. Since November 2015, more than 500 anti-government protestors have been killed and thousands of others arrested while demanding land reform and an end to human rights violations.

Last year, activists leaked the papers for the country's 12th grade national exams and called for the postponement of the exams due to a school shutdown in the regional state of Oromia. Mohammed Negash of DW's Amharic service said it appeared the government had taken preventive measures to avoid a recurrence of the incident. Negash said he was hopeful it was only a temporary measure and that things would return to normal once the exams were over. 

The government, through its public relations director in the Office for Government Communications Affairs, Mohammed Seid, said the move was 'proactive.' Speaking to Reuters, Seid said: "We want our students to concentrate and be free of the psychological pressure and distractions that this brings." 

About 1.2 million students are currently taking part in grade 10 national exams, with another 288,000 preparing for the grade 12 university entrance exams that will take place next week. Algeria's government took a similar step in June 2016 when it blocked social media networks in order to curb cheating in secondary school exams.