The Comoros’ election body has delayed releasing presidential election results.
Reports say opposition candidates have rejected the outcome.
Observers from the African Union, Common Market of Eastern and Southern Africa and Eastern African Standby Force said on Monday the voting process was full of irregularities that led them to conclude it lacked credibility or transparency.
The government has banned public gatherings in the capital, Moroni.
On Monday, police used tear gas to disperse demonstrators led by opposition leaders protesting over the vote.
The presidency used to be rotated around the three Indian Ocean islands that make up the country every five years, a system which was put in place to stop constant coups.
But a referendum last year increased term limits, allowing President Azali Assoumani to run for re-election.
He is running against 12 opponents but is widely expected to win.