* Machinegun-mounted pro-Ouattara convoy heads into Abidjan
* U.N. and French helicopters attack Gbagbo bases
* Sustained fire, explosions near presidential palace
(Adds Ouattara camp claiming control of Gbagbo residence, paragraph 4; details)
By Mark John and Ange Aboa
ABIDJAN, April 4 (Reuters) - U.N. and French helicopters attacked Laurent Gbagbo’s last strongholds in Abidjan on Monday as forces loyal to Ivory Coast presidential claimant Alassane Ouattara streamed into the city in a “final assault”.
Explosions and gunfire rang out from the direction of the Presidential Palace, the state broadcaster RTI, and one of two bridges connecting the lagoon-side city to the airport — among the last strategic footholds held by the incumbent leader who has refused to step down since a November election.
Attack helicopters commanded by the United Nations mission in the West African country fired missiles at Gbagbo’s military bases, and near his official residence, causing huge explosions that shook nearby homes and smashed windows, witnesses said.
A spokesman for Ouattara’s government later said pro-Ouattara forces seized Gbagbo’s residence, situated in the leafy Cocody neighborhood, but the information could not independently confirmed and a pro-Gbagbo military source who asked not to be named denied it.
“Yes, they are inside his residence. They are in control. But if (Gbagbo’s) there or not I don’t know,” Ouattara government spokesman Patrick Achi told Reuters by phone.
France said its military was supporting the U.N. peacekeeping force at U.N. request, targeting Gbagbo’s heavy weapons stockpiles and armoured vehicles equipped with heavy guns and rocket launchers.
Several thousand pro-Ouattara fighters entered Abidjan from the north in a convoy of transporters, pick-ups mounted with heavy machineguns, and 4x4s loaded with fighters bearing Kalashnikovs and rocket launchers.
Their commanding officer, Issiaka “Wattao” Ouattara, told Reuters he had 4,000 men with him plus another 5,000 already in the city. Asked how long he would need to take Abidjan, Wattao said: “We’ll know when it starts, but it could take 48 hours to properly clear (the city).”
Gbagbo has refused to cede power after an election last November that U.N.-certified results showed Ouattara won. Gbagbo rejected the results and accused the United Nations of bias. The standoff that followed has now turned into a resumption of the civil war of 2002-3.
After swiftly taking control of most of the country, pro-Ouattara forces have met fierce resistance in Abidjan, where Gbagbo’s troops are holding on to positions around the presidential palace, Gbagbo’s residence and state television.
After several days of fighting in Abidjan, nervous citizens who had been trapped in their homes by the fighting ventured out early on Monday morning to get food and water.
Hours later, a fresh wave of pro-Ouattara troops entered the city and secured a stretch of 5 km (3 miles) of deserted motorway south of their entry point into Abidjan, heading past the pro-Gbagbo neighbourhood of Yopougon.
Civilians walked on footpath bridges above the motorway holding their hands in the air.
Speaking on Sunday on the pro-Ouattara TCI television channel, Ouattara’s prime minister Guillaume Soro said their strategy had been to encircle the city, harass Gbagbo’s troops and gather intelligence on their arsenal. “The situation is now ripe for a lightning offensive,” he said.
France, the former colonial power, has about 12,000 nationals in Ivory Coast. Its 1,500-strong garrison had already mounted patrols in Abidjan and taken control of the airport.
On Monday, President Nicolas Sarkozy’s office said it would join the United Nations peacekeeping contingent in trying to neutralise heavy weapons belonging to troops loyal to Gbagbo.
Separately, the French Foreign Ministry said two French nationals and several other people had been abducted in Abidjan. France’s Europe 1 radio reported five people had been abducted in all, from a hotel in the city’s business district.
It had been expected that Ouattara’s forces would quickly overrun Gbagbo’s troops after defections by senior officers, but they have managed to withstand the assault so far, and regained control of state broadcaster RTI.
In a boost to Ouattara’s forces, U.N. and French helicopters fired at pro-Gbagbo military camps late on Monday, and a base held by Gbagbo’s elite Republic Guard securing one of the city’s two main bridges was seen in flames.
“We saw two UNOCI (U.N. mission in Ivory Coast) MI-24 helicopters fire missiles on the Akouedo military camp,” one witness told Reuters. “There was a massive explosion and we can still see the smoke.”
Other witnesses said blasts had smashed out windows at homes near the base and residents were crying and screaming in the streets in apparent panic.
The top United Nations official in Ivory Coast had told the BBC earlier on Monday that the mission was “planning action” after 11 peacekeepers were wounded by pro-Gbagbo forces, and after civilians were killed by heavy weapons fire.
More than 1,500 people have been killed since the violence began five months ago and human rights watchdogs have called on both sides to exercise restraint.
The ICRC said it stuck by an estimate of 800 killed in the western town of Duekoue alone in intercommunal violence on one day last week, after Ouattara forces had taken control of the town. Ouattara’s camp says the toll is “exaggerated”.
The yield on Ivory Coast’s $2.3 billion 2032 bond, on which it defaulted at the end of January, rose slightly on Monday. Cocoa prices, meanwhile, were mixed as dealers waited to see if the assault by Ouattara forces would unseat Gbagbo and pave the way for a resumption of exports from the world’s top cocoa producer. (Additional reporting by Emmanuel Braun outside Abidjan, Tim Cocks, Ange Aboa, and Loucoumane Coulibaly in Abidjan, Ed Cropley in Johannesburg, Sujata Rao and Carolyn Cohn in London, Writing by Richard Valdmanis and Bate Felix; Editing by Giles Elgood and Philippa Fletcher)