By Tim Cocks and Ange Aboa
ABIDJAN (Reuters) - Forces loyal to Ivory Coast's Alassane Ouattara have seized the major cocoa port of San Pedro, extending a nationwide offensive that has left incumbent Laurent Gbagbo isolated in the main city, Abidjan.
In a blow to Gbagbo, his army chief of staff, General Phillippe Mangou, sought refuge in the South African ambassador's residence in Abidjan. A South African spokesman denied rumours that Gbagbo was on the way to South Africa.
Residents and combatants from both sides said the pro-Ouattara forces were in control of western port town of San Pedro, and that it was now largely calm apart from some sporadic shooting.
Reuters witnesses in the main city, Abidjan, Gbagbo's last remaining stronghold, said the streets were virtually empty and gunfire could be heard overnight and on Thursday morning, but it was not clear who was involved.
Gbagbo has resisted pressure from the African Union and the West to step down since a presidential election last November, which U.N.-certified results showed he lost to Ouattara by an 8-point margin, sparking a deadly power struggle.
But forces loyal to Ouattara launched an offensive this week on three fronts, and towns across the country fell, mostly without resistance, one after another as they swept south.
Cocoa prices have fallen about 9 percent since on the push. The capture of San Pedro, which ships half of the top grower's beans, could, in theory, mean a resumption in exports.
Diplomats said on Thursday that European Union sanctions, including an embargo on cocoa shipments from San Pedro, would remain in place and if any exemption were discussed it would take four or five days to come into force.
The disputed election that was meant to draw a line under the 2002-3 civil war has instead reignited it, as rebels who control the northern half of the country and now back Ouattara advanced south into Gbagbo's territory from all sides.
"We have taken the port of San Pedro. Gbagbo's forces have all left. We are in full control," a military spokesman for Ouattara's forces, Seydou Ouattara, told Reuters.
Residents in the western port town said pro-Ouattara force were patrolling the streets after little resistance was put up.
"(Pro-Ouattara) soldiers came this morning and told us to stay in our homes. They assured us they wouldn't kill us," said resident Ibrahim Yao.
The push south has raised hopes across Ivory Coast's north, where Ouattara's support is the strongest, for a swift end to the crisis.
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 to and his youth supporters have sought to join the army.
Machinegun fire rang out Yopougon near the city while heavier weapons were heard closer to the centre of Abidjan, Reuters witnesses said. Shops were closed and the streets were deserted.
Thousands of prisoners escaped the main jail in Abidjan following a gun battle, residents and a military source said.
Ouattara's prime minister Guillaume Soro told French radio on Wednesday that Gbagbo had hours to leave power peacefully.
WEST AFRICANS SLAUGHTERED
At least 472 people have been confirmed killed since the standoff began, according to the United Nations, and a humanitarian crisis is worsening, with a million people displaced from the commercial capital Abidjan alone.
But the real figure is likely to be much higher.
State media has said the rebels are foreigners from neighbouring West African states, prompting many killings.
Pro-Gbagbo militias killed 37 West African immigrants in a village in the west on March 22, Human Rights Watch said.
"Witnesses in Ivory Coast told Human Rights Watch that armed men, some in uniform and others in civilian clothes, massacred the villagers, presumed to be Ouattara supporters," HRW said, warning that Gbagbo may be guilty of "crimes against humanity."
Thousands of people have sought shelter in churches and public buildings and at least 112,000 have crossed into Liberia to the west.
The U.N. Security Council overnight imposed travel bans and asset freezes on Gbagbo, who is already under European Union and U.S. sanctions. The resolution also sought to prevent use of heavy weapons in the main city, Abidjan.
Until the push south this week, the worst of the violence had centred on Abidjan, where anti-Gbagbo insurgents, who do not necessarily support Ouattara, have seized parts of town.
In a sign violence could spin out of control, the army called on Gbagbo's often violent youth wing to enlist in the military. 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.
(Writing by David Lewis and Tim Cocks; Editing by Giles Elgood)