Voters are going to the polls in an election some opposition parties are describing as a power grab.

People in Comoros are casting their ballots in the archipelago’s presidential elections, with incumbent Azali Assoumani widely expected to win a new term in a vote that rivals say has been hijacked.

The main opposition alleged that irregularities at several polling stations reported on Sunday by the electoral commission amounted to a “coup d’etat” and called for public “resistance”.

“We candidates declare the current government illegitimate … [we] call on the people to resist and mobilise against it,” Soihili Mohamed, the head of the Union of the Opposition group and a former deputy president, told journalists on Moroni island.

Azali confirmed but played down sporadic incidents after voting at a school in Mitsoudje on the main island Grande Comore.

“I’ve been told there have been some problems; it’s not a surprise,” he said.

“We were aware during the campaign there are some people who were not out there to win but to prevent the vote taking place.

“The situation is under control,” he added, expressing “confidence” over a win.

An electoral commission official told AFP news agency that a dozen booths had been vandalised on the island of Anjouan, while witnesses said several stuffed ballot boxes had been found and some opposition poll assessors had been prevented from going about their duties.

“Given that my delegates have been prevented from entering polling stations … I shall never recognise the results,” Mahamoudou Ahamada, candidate of opposition party Juwa, said after voting on Grande Comore.

The Supreme Court had barred some of Azali’s major rivals, including former President Ahmed Abdallah Sambi, accused of corruption, from running.

Some 300,000 voters were expected to turn out, with polling stations opening at 8:00am (05:00 GMT).

A woman casts her ballot for the presidential election at a polling station of Mitsoudje [Gianluigi Guercia/AFP]

The poll comes after Comorans voted in a referendum that was boycotted by the opposition to support the extension of presidential mandates from one five-year term to two, rotating among the three islands.

The opposition fears that Azali, a native of Grande Comore and last elected in 2016, could hold power for 10 more years until 2029.

The referendum last July led to violent protests on Anjouan, which would have taken over the presidency in 2021.

“I hope my choice will be respected,” Allaoui Elarif, 70, told AFP.

“I don’t expect any trouble, demonstrations here. It is afterwards, at the election commission where I am afraid they will cheat.”