Heavy firing in Ivory Coast's Abidjan before march

ABIDJAN (Reuters) - Heavy weapons were fired near the Abidjan base of the internationally-endorsed winner of a disputed presidential poll on Thursday before a planned march by his supporters to seize the state broadcaster, witnesses said.

"There is shooting all over the place. There is artillery. There are explosions. It is all coming from the direction of the Golf Hotel," said one witness. A second witness living near the hotel also confirmed heavy weapons fire.

Security forces on pick-up trucks mounted with machine guns had blocked roads leading to the waterside hotel, which Alassane Ouattara, rival to incumbent leader Laurent Gbagbo, is using as a base under guard of U.N. peacekeepers.

Gbagbo, declared election victor by Ivory Coast's highest legal body, controls state institutions and police and troops had massed on the streets after Ouattara's allies called for marches to take over state buildings.

Sustained machine gun and rifle fire was heard in the city earlier on Thursday. It was not clear where it was coming from.

Tensions have been steadily mounting in the world's top cocoa grower after a poll intended to heal a north-south division created by a 2002-2003 conflict but which instead has raised fears of unrest and a potential return to all-out war.

A demonstration in the capital Yamoussoukro on Wednesday was broken up by police firing tear gas and live rounds. At least one person was killed, several witnesses said.

Two witnesses said one demonstrator was killed by a police bullet but police spokesman Diagouri Honore said the person killed was a police officer.

"One of the demonstrators was armed and fired on him. I don't have the details of the circumstances, but we know it was a policeman killed," he said.

TAX THREAT

A top-level African Union delegation was due to meet Nigerian President Goodluck Jonathan, current chief of the West African bloc ECOWAS on Thursday, in efforts by African countries to resolve the crisis peacefully.

Election commission results showed Ouattara won last month's election. But the pro-Gbagbo Constitutional Council scrapped nearly half a million votes in Ouattara bastions to hand victory to Gbagbo on grounds of fraud, causing international outrage.

Leaders around the world have recognised Ouattara as president of Ivory Coast, but Gbagbo remains in control of the military, state television and radio and government buildings.

Cocoa futures have risen to four-month highs on fears of potential disruption to supplies. March cocoa futures were up $23 or 0.8 percent at $3,002 a tonne early on Thursday.

In a move that could threaten a key source of revenues for Gbagbo's administration, Ivory Coast's chamber of commerce this week wrote to its members and advised them not to pay any taxes.

In the letter, seen by Reuters, Jean-Louis Billon, the president of the organisation, said businesses have had to hear the brunt of Ivory Coast's crisis and the status quo with two administrations made paying taxes impossible.

Separately, Billon was blocked from leaving the country on Wednesday by the police, who seized his passport.

(Reporting by Ange Aboa and Loucoumane Coulibaly in Abidjan, Joe Brock in Abuja and David Lewis in Dakar; writing by Tim Cocks; editing by Mark John and Philippa Fletcher)