African mediators flew in to Ivory Coast on Monday, armed with inducements but vowing no compromise in their bid to get incumbent Laurent Gbagbo to stand down following disputed polls.

Kenya's Prime Minister Raila Odinga, the African Union's envoy, arrived in Abidjan, with three heads of state due to join him to try to end the stand-off between Gbagbo and the man the world says beat him to the presidency, Alassane Ouattara.

"It is necessary to give Mr Gbagbo the necessary sweets to make it easy for him to step down," said Ibrahim Ben Kargbo, the information minister of Sierra Leone, whose leader is a member of the West African presidential troika.

Ben Kargbo did not elaborate on what form those inducements would take, but added: "We are trying to create a peaceful exit, for him to leave the office in a respectable manner."

Gbagbo has refused to step down in favour of Ouattara, who has been recognised as the election winner by most of the world, in a tense five-week stand-off that has sparked international condemnation and fears of a civil war.

"We are going strictly by the communique circulated on Christmas Eve clearly stating that President Gbagbo should step down. This is our working document," Ben Kargbo told AFP in Freetown.

Sierra Leone President Ernest Koroma, Benin's Boni Yayi and Cape Verde's Pedro Pires were dispatched by the 15-nation Economic Community of West African States (ECOWAS) which has threatened military action to remove Gbagbo if he refuses to cooperate.

Odinga, who has previously called for Gbagbo's removal by force, said on Sunday that he would keep an open mind on finding a solution.
"We don't want to pre-empt anything. We just want to talk to him (Gbagbo) and we will see what happens," Odinga told AFP. "It depends on how Gbagbo wants to handle it."

The four African leaders are expected to meet Gbagbo and then Ouattara, who is holed up in a hotel resort in Abidjan, protected by UN troops.

Current ECOWAS head, Nigerian President Goodluck Jonathan, has said the regional body will decide by Tuesday how to handle the impasse, amid unconfirmed reports of mass graves filled with Ouattara supporters.

West African regional military chiefs met in Abuja last week and set in motion plans to oust Gbagbo if negotiations fail, according to a Nigerian defence spokesman. A follow-up meeting to fine-tune the "last-resort" plan is scheduled for Mali on January 17 and 18.

Tensions have risen steadily since Gbagbo and Ouattara both claimed victory in a November 28 presidential run-off vote that it was hoped would end a decade of crisis in Ivory Coast.

Both men have fired off a series of deadlines at each other since then, with Ouattara's latest call for Gbagbo to quit expiring unheeded at midnight on New Year's Eve.

Ouattara's once-plush hotel is protected by a small contingent of lightly armed former rebel fighters known as the New Forces and 800 United Nations troops equipped with armoured vehicles and re-supplied by helicopter.

It is surrounded by Gbagbo's well-armed regulars, the Ivory Coast Defence and Security Forces (FDS), but there are fears of a repeat of 2004 violence if Gbagbo's supporters make good on a threat to send unarmed youths to storm the hotel.

The UN says that at least 179 people have been killed in post-election violence but that it has been unable to fully investigate because of attacks on its personnel, while UN rapporteurs said they feared the violations being committed amounted to "crimes against humanity".

UN Secretary General Ban Ki-moon told Ouattara in telephone talks that UN peacekeeping forces in the West African nation had been told "to do everything possible" to gain access to the alleged sites of mass graves, a spokesman said.