Brazzaville, March 16 — Internet access across the Republic of the Congo was abruptly disrupted on Sunday as voters headed to polling stations to take part in the country's presidential election, a global internet monitoring group said.

Data published by NetBlocks indicated a "major disruption" to nationwide connectivity, affecting most users and making it difficult for citizens and media outlets to follow election developments in real time.

The group noted that similar outages have occurred in the past. During the presidential election in March 2021, internet access in the country was also reported to have been almost entirely cut off for about three days.

Under the electoral system in the Republic of the Congo, a candidate who secures an outright majority in the first round is declared the winner. If no candidate achieves that threshold, a run-off vote is held between the two leading contenders.

Incumbent President Denis Sassou Nguesso is seeking another term in office. He first came to power in 1979, lost an election in 1992 and went into exile in France before returning in 1997 following an armed uprising that ousted then-president Pascal Lissouba.

Since then, Sassou Nguesso has won successive presidential elections in 2002, 2009, 2016 and 2021, with official results from the most recent vote showing him securing more than 88 percent of ballots cast.

He is facing six challengers in the current election, including former lawmaker Mabio Mavoungou Zinga and lawyer Joseph Kignoumbi Kia Mboungou.

The internet shutdown has raised concerns among observers about access to information and the ability of voters and election monitors to track the conduct and transparency of the vote.