ABIDJAN (Reuters) - A U.N. investigation into alleged human rights abuses in Ivory Coast will be fruitless without the cooperation of authorities loyal to incumbent leader Laurent Gbagbo, an official in his administration said on Sunday.

The country was plunged into crisis when Gbagbo refused to step down after a disputed election in November, leading to an outbreak of violence in a nation still divided since a civil war in 2002 and 2003.

The electoral commission, world leaders and the U.N. General Assembly have recognized Gbagbo’s rival Alassane Ouattara as the winner of the election.

“The Secretary-General told President Ouattara that he was alarmed by the reports of egregious human rights violations,” U.N. spokesman Martin Nesirky said in a statement, referring to a telephone conversation between U.N. chief Ban Ki-moon and Ouattara on Saturday.

Ouattara’s supporters say they are being hunted down and killed or kidnapped at night by pro-Gbagbo forces. The U.N. has put the death toll from the violence at more than 170, the United States at over 200.

The U.N. peacekeeping mission in Ivory Coast, known as UNOCI, said last month pro-Gbagbo forces were blocking access to what could be a mass grave near Abidjan. U.N. diplomats told Reuters UNOCI was still barred from the site.

“He (Ban) said UNOCI had been instructed to do everything possible to gain access to the affected areas both for prevention and to investigate and record the violations so that those responsible will be held accountable,” Nesirky said.

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The cabinet director of Gbagbo’s Interior Ministry, Vehi Tokpa, told Reuters by telephone such an investigation would go nowhere without the cooperation of the Ivorian security forces.

“How can the United Nations do an investigation in Ivory Coast without the participation of the Ivorian authorities? What is the value of this?” he said.

“When there are truths to clear up, we shall base them on facts, not declarations.”

If there was evidence of a mass grave, he said, the United Nations must “tell us ... where it is.”

GBAGBO DEFIANT

Defiant in the face of growing international pressure, Gbagbo reiterated a call on state television on Saturday for the peacekeeping mission to leave Ivory Coast, accusing it of opening fire on civilians.

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The mission rejected a similar accusation on its website three days ago as “lies” and said the state-owned broadcaster was spreading misinformation to incite hatred against it.

Residents of an area alleged to be the site of a mass grave said last month the Ivorian military had closed off the site and chased away anyone who tried to gain access.

Ouattara has asked for the International Criminal Court in The Hague to send a mission to Ivory Coast to investigate reports of post-election violence by pro-Gbagbo forces.

He reiterated the request in his call with Ban on Saturday.

Three presidents from the West African regional bloc ECOWAS are planning a second round of talks on January 3 with Gbagbo to try to persuade him to cede power to Ouattara or face an operation to remove him by force.

A statement issued by the African Union on Sunday said they would be joined by Kenyan Prime Minister Raila Odinga, who has called for the use of force to oust Gbagbo and whose own electoral dispute with President Mwai Kibaki, accused of rigging the Kenyan election in 2007, let to ethnic bloodshed in which 1,300 people were killed.

The United Nations has expressed concern that the homes of political opponents of Gbagbo in the main city of Abidjan have been marked to identify their occupants’ ethnicity, indicating that the country could be heading for ethnic violence.