Police fired teargas and rubber bullets Monday to disperse more than 100 opposition supporters as Comoros awaited the results of elections President Azali Assoumani is tipped to win, AFP correspondents saw.
Two people were injured -- a protester and a plainclothes policeman -- when the group began marching towards the capital Moroni's Independence Square.
The country is awaiting the results of Sunday's presidential elections which the opposition claim was riddled with flaws.
Azali's main rivals, the Union of the Opposition, alleged that irregularities at several polling stations reported by the electoral commission on Sunday amounted to a "coup d'etat" and called for public "resistance".
An electoral commission official told AFP on Sunday that a dozen booths were vandalised during polling.
Witnesses said several stuffed ballot boxes were found on Anjouan island -- an opposition stronghold.
Some opposition poll monitors were also prevented from conducting their duties, they added.
Counting started Sunday night at the National Assembly under police guard.
"We have counted (ballots from) Moroni and surrounding areas," an electoral commission official told AFP.
The commission was waiting for boxes from Anjouan and Moheli, two of the three islands that make up the archipelago, the source said, adding that results would be released within the legally required five days.
'Some problems - it's not a surprise'
Seven opposition candidates flanked by dozens of supporters marched on Anjouan's National Assembly to "prevent ballot boxes from reaching (the capital) Moroni," said Mahamoudou Ahamada, a candidate for the opposition party Juwa said.
Police quickly dispersed the group.
"We candidates declare the current government illegitimate... (we) call on the people to resist and mobilise against it," the country's former deputy president and now head of the Union of the Opposition, Soihili Mohamed said on Sunday.
Azali's campaign director Houmed Msaidie described the opposition claims as "pathetic", accusing them of creating "a climate of panic to invalidate the electoral process".
"If there was fraud, they should go to the appropriate authorities," he told AFP.
Azali played down the incidents.
"I've been told there have been some problems -- it's not a surprise," he said after casting his ballot at a school in Mitsoudje on the main island Grande Comore, adding he was confident of victory.
Some 300,000 voters were called out to vote in the Indian Ocean archipelago, which has a two-round system for electing the president.
The mainly Muslim nation of 800,000 people is one of the world's poorest and most coup-prone states -- there have been more than 20 attempted or successful power grabs since independence from France in 1975.
The Supreme Court barred some of Azali's major rivals, including former president Ahmed Abdallah Sambi, accused of corruption, from running.
Azali staged the poll after Comorans voted in a referendum, boycotted by the opposition, to support the extension of presidential mandates from one five-year term to two.
The change upset a fragile balance of power established in 2001 that sought to end separatist crises on Anjouan and Moheli, and halt the endless cycle of coups.