Opposition parties and some civil society groups boycotted the vote, saying the amended law was designed to keep President Faustin-Archange Touadéra in power for life.

They said the referendum lacked transparency and there was limited time given to debate its provisions.

Nearly two million people registered to vote, and turnout was estimated by those watching the poll as low.

The proposed law abolishes the presidential two-term limit and extends the term in office from five to seven years.

It also bans politicians with dual citizenship from running for president.

Under the proposed changes, there will be an office of the vice-president, to be appointed by the president. The senate will be scrapped, transforming parliament to a single chamber.

The number of supreme court judges have been increased from nine to 11, and the president and the national assembly can now select three judges each. Previously they could only select one each.

The president and members of his United Hearts Party have claimed they are following the will of the people. The opposition has called it a “constitutional coup”.

President Touadéra has struggled to quash rebel groups that have controlled large swathes of the country since he came into power in 2016, a spill from another rebellion in 2013 which ousted former President François Bozizé.

He turned to Russia for help in tackling the rebels in 2018. Ahead of last Sunday's vote, dozens of fighters from Russia’s Wagner mercenary group were seen arriving in the country.