Troops from the Comoros archipelago in the Indian Ocean have recaptured most of the island of Anjouan after a year-long rebellion, officials say.
They said troops backed by an African Union force had taken Anjouan's main city and airport with light resistance.
But fighting continues in some areas and the whereabouts of rebel leader Col Mohammed Bacar is unclear.
His re-election as president of the semi-autonomous island of Anjouan last
year had been declared illegal.
Defence Minister Bacar Dossar said coalition forces had not yet secured total control of the island and were "trying to flush out a pocket near [Col Bacar's] residence in Barakani".
There were other small areas of resistance, he told the BBC, adding that so far neither the AU troops nor the Comoros army had suffered any casualties.
Officials said government forces had arrested several high-ranking aides of Col Bacar, but were still looking for the rebel leader himself.
About 450 Comoran and AU troops landed in a seaborne assault at dawn on Tuesday. Mortar and machine-gun fire was heard.
The invading force captured the airport at Ouani and the main city, Mutsamudu. The presidential palace was abandoned.
The Comoran troops are being supported by a nearly 1,500-strong AU force, including Tanzanian and Sudanese soldiers.
As the assault was launched on Monday night, Comoran President Ahmed Mohamed Sambi said: "I have ordered the Comoran army and the forces of our country's friends to bring Anjouan back under the rule of law and free her citizens."
Residents of the island were pictured greeting the government forces with jubilation as they patrolled through the streets, with some of the crowds chanting "Bacar is a dog".
Five boats carrying the Comoran and AU troops had left the island of Moheli overnight on Sunday, while a helicopter dropped leaflets over Anjouan warning citizens that the assault to retake the island would begin in hours.
The Comoros archipelago has had a fractious history since independence from France in 1975, experiencing more than 20 coups or attempted coups.
The three main islands of the archipelago lie 300km (186 miles) off Africa's east coast north of Madagascar.
Mr Bacar was elected president of semi-autonomous Anjouan in 2002. His re-election in 2007 was declared illegal by the federal authorities on Grand Comore who declared Anjouan to be in rebellion.
The AU condemned Mr Bacar's move and agreed to provide troops to topple him.