A UN spokesman said the operation was launched a day after forces loyal to the incumbent president fired rocket-propelled grenades and mortar rounds at the Golf Hotel, injuring one peacekeeper. It's believed the weapons that were used are amassed at Gbagbo's residence, UN spokesman Hamadoun Toure said.

Alassane Ouattara, the internationally recognized president of the country, has been using the hotel as his headquarters since November's disputed elections.

The French ambassador's residence came under fire on Friday, according to Frederic Daguillon, commander of French forces in Ivory Coast.

"We are pursuing our operation to neutralize Gbagbo's heavy weapons," Toure told Reuters.

Two residents from nearby neighbourhoods reported seeing two Mi-24 attack helicopters and one French helicopter open fire on the residence. One resident reported seeing smoke rise from the compound, where Gbagbo is holed up in a bunker.

After a decade in power, he still refuses to step aside even though the United Nations has ruled that he lost the presidential election to Ouattara.

After four months of diplomacy, Ouattara gave the go-ahead for a military intervention led by fighters from a former rebel group.

They swept across the country, advancing hundreds of kilometres and taking dozens of cities in a matter of days before being held up at the door of Abidjan, Ivory Coast's biggest and most strategically important city.

Gbagbo's forces broke out of the presidential compound Saturday and advanced into position in the downtown core and near the Golf Hotel.