|Cote d'Ivoire has been in turmoil since November's vote, which both Gbagbo and Ouattara claim to have won [Reuters]
Fierce fighting has broken out in Cote d'Ivoire's western town of Duekoue between forces loyal to Laurent Gbagbo, the incumbent president, and his internationally recognised rival, Alassane Ouattara, residents and combatants say.
Rebels who took control of the north of the country during the 2002-3 civil war and are now backing Ouattara said on Monday they had taken Duekoue, which has been under Gbagbo's control for nearly a decade.
Duekoue lies in a region that produces around 250,000 tonnes of cocoa a year in the west African nation, which is the world's top grower.
"The town of Duekoue has been under our control since 7am (0700 GMT). We are conducting search operations throughout," said Lacine Mara, a spokesman for pro-Ouattara forces in the west.
Gbagbo's forces confirmed the fighting, but said they remained in control of at least part of the town.
"Our men have been in combat since about 2am (0200 GMT) this morning with the rebels, who tried to take the town. We control one part and they control the other," said Yao Yao, operations chief of Gbagbo's Front for the Liberation of the Great West (FLGO) militia.
A Reuters reporter in the main city of Abidjan also reported shooting and heavy arms fire on Monday, from areas where pro-Ouattara fighters seeking to oust Gbagbo are pushing towards the city centre.
Cote d'Ivoire has been in turmoil since last November's disputed elections, with security forces backing Gbagbo regularly clashing with Ouattara's supporters, mostly rebels calling themselves the Republican Forces.
The UN estimates more than 400 people have been killed since the election and up to one million have been driven from their homes. Tens of thousands of people have had to seek refuge in neighbouring Liberia and Ghana.
Gbagbo insists he won the election though the United Nations, the African Union and ECOWAS, the west African economic grouping, recognise Ouattara as the winner. He remains holed up in an Abidjan hotel, protected by a ring of UN peacekeepers.
Monday's fighting came only days after Ouattara rejected an African Union-appointed envoy from the island nation of Cape verde to mediate the crisis, saying the appointee has personal ties with Gbagbo.
Pro-Ouattara forces have already seized four towns in the west and Gbagbo's forces fear that if they capture enough important towns, they will be able to march south to the port of San Pedro, which ships about half of Cote d'Ivoire's cocoa crop.
"The rebels want to take Duekoue and Guiglo so they can easily descend on San Pedro," Yao Yao said. "We won't let them."
Last week, around 15,000 pro-Gbagbo youths turned up at the army's headquarters to enlist, raising fears that all-out civil war is now unavoidable.