* Heavy fighting heard in central Abidjan, French patrol
* Ouattara camp says Gbagbo has just hours left in power
* Gbagbo army chief takes refuge in S.African residence
(Adds Ouattara curfew, U.N. controlling airport)
By Loucoumane Coulibaly and Tim Cocks
ABIDJAN, March 31 (Reuters) - Heavy weapons fire rang out in central Abidjan on Thursday after presidential claimant Alassane Ouattara’s forces marched into Ivory Coast’s main city, and his camp said incumbent Laurent Gbagbo had just hours left in power.
Residents reported heavy fighting near the state broadcaster, RTI, as well as in neighbourhoods in the south of the city after pro-Ouattara forces swiftly advanced on the lagoon-side city from several directions.
Gbagbo’s elite forces took positions around the presidential palace while French soldiers were also deployed in the city to protect foreign residents. A United Nations helicopter gunship flew overhead.
Gbagbo has refused to step down since a November election that U.N.-certified results showed he lost to Ouattara, triggering a bloody standoff that has killed hundreds and rekindled the country’s 2002-3 civil war.
“I call on you to serve your country ... It is time to join your brothers in the Republican Forces,” Ouattara said in a statement aimed at encouraging members of the security forces still loyal to Gbagbo to defect.
South Africa’s government said that Gbagbo’s army chief of staff, General Phillippe Mangou, had sought refuge at its ambassador’s residence in Abidjan, in one of the biggest blows yet to Gbagbo’s grip on power.
The U.S. government said Gbagbo had been “significantly” weakened amid defections and the disintegration of his forces.
Security sources said some of the gendarmerie had joined Ouattara’s camp but others remained loyal to Gbagbo. U.N. troops were now also in control of Abidjan airport after pro-Gbagbo forces abandoned it, a security source and U.N. sources said.
Ouattara’s prime minister, Guillaume Soro, said Gbagbo had only two or three hours left in power and the “game is over”.
In a dramatic four-day sweep, pro-Ouattara forces reached Abidjan after taking the key cocoa port of San Pedro and the official capital Yamoussoukro, having advanced hundreds of kilometres since the start of the week.
His government, until now blockaded in an Abidjan hotel, announced a three-day overnight curfew and ordered the closure of land, air and sea borders until further notice, according to an Interior Ministry statement.
Ivory Coast is the world’s biggest cocoa producer. The power struggle had pushed prices higher, but they have tumbled since Ouattara’s push began.
The capture of San Pedro, which ships half of the country’s production, could kick-start the flow of beans that dried up in January due to sanctions, but diplomats said any easing of EU measures would take days.
“There is heavy shooting next to RTI (state radio and television) at the moment,” said Justin Bohou, who lives in the Cocody neighbourhood of Abidjan.
Reuters witnesses said heavy weapons fire also came from Treichville and Marcory, south of the centre of town, where pro-Gbagbo’s forces had taken up positions.
French troops stationed in the former French colony patrolled parts of Abidjan to prevent attacks on foreigners.
There were widespread reports of looting.
“Militarily, I think it is over. But I don’t think the situation is totally under control as there is likely to be lots of pillaging,” a security source said, asking not to be named.
Gbagbo has resisted pressure from the African Union and the West to step down since the November poll, and has been the target of sanctions by the United States, the European Union and the U.N.
Pro-Ouattara forces have pushed down towards Abidjan from the northwest and the northeast, so far meeting little resistance as Gbagbo’s regular army either withdraws or switches sides.
But, should Gbagbo decide to put up a fight, Ouattara’s forces risk becoming bogged down in bloody urban warfare in Abidjan, where pro-Gbagbo forces have retreated and his youth supporters have sought to join the army.
They have been fired up with anti-French, anti-foreigner and anti-U.N. propaganda, and on Wednesday the army started openly handing out weapons to them.
The U.N. reiterated calls for Gbagbo to step down and Washington called on all sides to exercise restraint.
State media said Gbagbo would speak on Thursday evening.
At least 494 people have been confirmed killed since the standoff began, according to the U.N., and a humanitarian crisis is worsening, with a million people displaced from Abidjan.
But the real figure is likely to be much higher.
“Casualty numbers, killed and injured, are running into the thousands,” said Pierre Kraehenbuehl, the International Committee of the Red Cross’s director of operations.
New York-based Human Rights Watch said it had documented the killing of 37 West African immigrants by pro-Gbagbo militia in a village in Ivory Coast’s west on March 22 alone.
Thousands of people have sheltered in churches and public buildings. At least 112,000 have crossed into Liberia. (Additional reporting by Ange Aboa in Abidjan, Mark John in Yamoussoukro and David Lewis in Dakar; Writing by David Lewis and Richard Valdmanis; Editing by Mark Trevelyan)