Abidjain: The United Nations peacekeeping force in Ivory Coast rejected isolated leader Laurent Gbagbo's demand that it pack its bags on Sunday, at the risk of provoking a showdown with his hardline supporters.

Gbagbo has ordered the 10,000-strong UN mission to leave, accusing it of arming rebels loyal to his rival Alassane Ouattara, but UN Secretary General Ban Ki-moon dismissed the ultimatum and called on him to step down.

Both Gbagbo and Ouattara claim to have won last month's presidential vote but, while the latter has been recognised as the victor by the international community, the incumbent is clinging doggedly on to power.

Tension has reached boiling point in the commercial capital Abidjan, where violence erupted on Thursday during a protest march by Ouattara's supporters, and where Gbagbo's loyalist armed forces are in an uneasy stand-off with the UN.

"We're going to continue our patrols but we're not seeking confrontation. There are sensitive areas where we don't go, near the presidency," said Hamadoun Toure, of the United Nations Operation in Cote d'Ivoire (UNOCI).

"We're increasing our vigilance, and we're ready for anything," he said.

Ivory Coast has been divided between north and south since 2002, when a failed putsch against Gbagbo triggered civil war. UNOCI deployed in 2004 to monitor a ceasefire, and was assigned to oversee last month's elections.

The UN monitors endorsed results from Ivory Coast's electoral commission that gave Ouattara victory in the November 28 run-off, but Gbagbo's allies on the Constiutional Council annulled the result, claiming fraud.

Now, both men style themselves president. Gbagbo retains control of the southern armed forces, the Abidjan ministries and the cocoa ports that are Ivory Coast's main source of revenue.

Ouattara is backed by former rebel fighters from the north -- the so-called "New Forces" -- but he and his government are holed up in a luxury golf resort in Abidjan, protected by a cordon of UN peacekeepers.

The United Nations, United States, former colonial power France, the African Union and Ivory Coast's West African neighbours in the ECOWAS bloc have all demanded that Gbagbo step aside and allow Ouattara to assume office.

Instead, there is every sign that the regime is hardening its stance.

On Thursday, troops and police fired on pro-Ouattara demonstrators in Abidjan, killing between 11 and 30 people. Opposition newspapers and radio stations have been banned, and the Golf Hotel is surrounded.

Late on Friday, gunmen in military uniform opened fire on a UN peacekeeping patrol returning to its Abidjan base. Then, on Saturday, Gbagbo's spokeswoman ordered French and UN troops to leave.

"The president of the Republic of the Ivory Coast has just asked for the immediate departure from Ivorian territory of UNOCI and the French forces that support it," Education Minister Jacqueline Lohoues-Oble said.

The UN Secretary General was unimpressed and rejected the order out of hand.

Ban condemned attacks on UN troops and said the force "will continue to monitor and document any human rights violations, incitement to hatred and violence, or attacks on UN peacekeepers."

Gbagbo's next move is not yet clear, but his most notorious lieutenant -- Minister for Youth Charles Ble Goude -- has called on his supporters to be prepared to fight to reassert Ivory Coast's sovereignty.

"Play time is over," Ble Goude declared on Saturday, a chilling phrase from a man who has been under UN sanctions since 2006 for "acts of violence by street militias, including beatings, rapes and extrajudicial killings".

"We are going to defend the sovereignty of our country until the last drop of our sweat. I urge all Ivorians to make themselves ready for this combat. We are going to totally liberate our country," he told AFP.

Ble Goude was to stage a rally of his partisans from the "Young Patriots" youth movement in the port district of Abidjan later Sunday. He is best known for leading bloody anti-French demonstrations in the city in 2004.

Then, French troops intervened to evacuate several thousand expatriates and more than 50 Ivorians died.