French troops airlifting the Japanese ambassador to safety after an attack by forces loyal to Ivory Coast's President Laurent Gbagbo Reuters

Fighting is continuing in Ivory Coast's main city, Abidjan, as French helicopters target forces loyal to the incumbent president Laurent Gbagbo, who is holed up in the country's presidential palace.

French troops staged a rescue mission to airlift the Japanese ambassador to safety after Gbagbo supporters broke into his residence, according to the Japanese foreign ministry.

The Japanese ambassador, Yoshifumi Okamura, and seven embassy employees sought refuge inside a safe room when Gbagbo fighters stormed the building and set up machine-guns and rocket-propelled grenades on the roof.

"I was blocked in my room and these people had seized my residence," Okamura said.

The ambassador's home is in the northern suburb of Cocody, near the presidential compound where Gbagbo's troops are holding off forces loyal to the president-elect, Alassane Ouattara.

Witnesses described a series of helicopter attacks near the compound in which at least one armoured vehicle was destroyed.

The French troops, part of the UN peacekeeping mission in Ivory Coast, appear not to have targeted the compound itself, but the operation is likely to further raise concerns over France's intervention in its former colony.

Gbagbo, who blames France for supporting the north of the country in the 2002-03 civil war, accused President Nicolas Sarkozy on Wednesday of masterminding an "assassination plot" against him after Ouattara forces tried unsuccessfully to storm the presidential compound.

A French armed forces spokesman, Thierry Burkhard, said the rescue operation was launched in response to a request from Japan and the United Nations.

"The Japanese authorities asked the United Nations to act and Unoci [the UN mission in Ivory Coast] asked Licorne [French troops] as it has the means to evacuate," he said.

Burkhard said French troops returned fire after they were shot at, "destroying at least one armoured vehicle and two pick-up trucks".

In a video provided by the French military, the forces are seen rappelling from a helicopter at night with night vision goggles, before the aircraft lands in a field to pick up a man, who appears to be Okamura.

No soldiers were injured but one of the Japanese officials was hurt.

Before Wednesday's assault on Gbagbo's residence, French ministers had confidently predicted that he could cede power within hours, ending the west African country's four-month crisis.

A UN spokesman in New York said negotiations with Gbagbo's camp were continuing, but it was not clear if they would lead anywhere. Gbagbo said on Wednesday he had no intention of stepping down.

Gbagbo told the French TV channel LCI that his army had called for a ceasefire, not surrender. "I'm not a kamikaze," he said by phone. "I love life. My voice is not the voice of a martyr, no, no, no. I'm not looking for death. It's not my aim to die.

"For peace to return to Ivory Coast, I and Ouattara, the two of us have to talk."

As the siege entered its third day, Abidjan residents trapped between the rival forces were desperately short of food and water.

"The fighting is terrible here. The explosions are so heavy my building is shaking," Alfred Kouassi, who lives near Gbagbo's residence in the commercial capital, told Reuters. "We can hear automatic gunfire and the thud of heavy weapons. There's shooting all over the place. Cars are speeding in all directions and so are the fighters."

Despite the fighting, civilians in the north of the city ventured outside to hunt for water and food. The streets were generally deserted save for these lone scavengers, many of whom walked with their hands in the air to show they were noncombatants.

"We haven't slept, we haven't eaten, we've had nothing to drink," said Mariam, 17, balancing a plastic container of water on her head and wearing a white T-shirt with the words "Obama Girl" emblazoned in black. "We are all going to die. Even the water we do get is dirty."

Other residents told Reuters they had walked 10 miles in their quest for drinking water. No one wanted to be out on the streets after a midday curfew imposed by Ouattara for fear of being taken for a pro-Gbagbo fighter.

Even in the outskirts of Yopougon, one of Gbagbo's strongest inner-city bastions, there were demands for him to step down – perhaps not surprising given the nearby presence of patrolling Ouattara troops who seized this neighbourhood on Monday.

Ibrahim Cisse, 29, said: "We are just waiting for him to go. It's Alassane who we are banking on now."

Rubbish was piling up in mounds by the roadside and decaying corpses identified by locals as pro-Gbagbo militiamen remained uncollected. "Tell the people the smell is going everywhere," 21-year-old Lassane Kone told Reuters.

Cash machines are empty, shops are shut and supplies are running out. Public services are paralysed, with ambulances unable to travel in case they are fired on. Those in need of medical attention have nowhere to turn. A war economy has sprung up rapidly. Mariam said the price of atieke – the ground manioc which is one of the staples of the Abidjan diet – had tripled in the space of a few days.

At a Ouattara base camp nearby, groups of women circulated between soldiers selling packets of atieke and little sachets of frozen fruit juices. "We are selling a bit so we can eat," said one vendor.