Guinea's President Alpha Conde has delayed Sunday's constitutional referendum and legislative polls for two weeks because of concerns raised by international observers about the electoral roll, he told state television late on Friday.

Earlier this week, the Organisation Internationale de la Francophonie, an organization of French-speaking governments, withdrew its poll-monitoring mission, citing the presence of 2.49 million "problematic" entries on the electoral register.

The claim increased pressure on Conde, 81, who many fear is holding a referendum on the constitution so he can extend his rule for 12 more years, despite the risk of mass unrest and a major dent in the health of Guinea's mining economy.

The new constitution would impose a limit of two six-year terms, up from the current two five-year terms. It does not specify whether terms served under the previous constitution would count, but Conde has suggested they would not.

"We accepted a slight postponement of the date of the elections," Conde said. "It is neither a capitulation or a retreat but loyalty to what Guinea was yesterday and today.”

At least 30 people have died since October in protests against the proposed constitutional changes. How the vote turns out could be a bellwether for a presidential election before year's end in the country, the largest African producer of the main aluminium ore, bauxite.

The opposition is boycotting the referendum an legislative elections, which it says will be a sham, and leading members have said they will prevent voting, without saying how.

Conde, who as an opposition leader was sentenced to death in absentia under one president and imprisoned under another, says the new constitution is badly needed to replace a 2010 version that was hastily drafted during military rule and defended his right to stand for a third term if nominated by his party.

His allies have touted progressive reforms, including a ban on female genital mutilation, compulsory education and new environmental laws.

The violence during recent protests has been largely limited to opposition strongholds, but U.N. High Commissioner for Human Rights Michelle Bachelet warned about the risk of wider unrest.

"Ethnic divisions are deepening, with increasing incitement to hatred and violence on social media and at political rallies," she said in a speech on Thursday.