Ethiopia said it had deactivated its internet services on Tuesday at the same time as more than a million year 10 students sat their national exams.

Google’s transparency report registered a sharp drop in national visits to the search engine, coinciding with the lead-up to the nation's year 10 and 12 school and university exams.

It's the second time in recent months that Africa's second most populous country has turned off its mobile data service, which most businesses and consumers rely on for internet access.

In July 2016, the government shut down access to Facebook, Twitter, and Viber after university entrance exam questions were leaked online, Africa News reports.

The leak led to the exam being cancelled.

While the Ethiopian government had admitted to temporarily disabling internet services, it offered no specific explanation for the countrywide outage.

The country's single telecommunications provider also disabled its data service for weeks last year amid fierce anti-government protests which have since been curbed under a state of emergency in place since last October.

"Mobile data has been deactivated," deputy communications minister Zadig Abrha told AFP, declining to elaborate further.

A spokesman for the state-owned Ethio Telecom did not respond to multiple requests for comment.

Home to both the headquarters of the African Union and the UN's Economic Commission for Africa, Addis Ababa has gained the nickname "Africa's political capital".

But officials at both institutions said their internet was cut on Tuesday afternoon but returned Wednesday, while average Ethiopians were still unable to connect via their phones or modems, which use mobile SIM cards.