A senior Congolese conservationist has been sacked after he was accused of colluding in major oil exploration plans by a British firm in one of Africa's oldest national parks.

Guy Mbayma Atalia, former scientific and technical director of the Congolese Institute for Conservation and Nature (ICCN), was dismissed after being implicated in a plot to attack anti-oil campaigners in the Democratic Republic of Congo's Virunga reserve.

"As of June 6, Atalia is no longer part of ICCN," said an institute statement obtained by AFP on Monday.

Human Rights Watch (HRW) accused Atalia of threatening to kill opponents of British energy firm Soco, which had been prospecting for oil in Virunga, home to 3,000 species including endangered mountain gorillas.

The former director is alleged to have "warned (a park warden) that if he continued to oppose Soco's activities in the park, (the warden) would be killed," according to a June 4 report by HRW.

Another ranger told HRW that Atalia had instructed him and five other park guards to campaign on behalf of Soco.

"We were each paid $20 (15 euros) a day for 35 days," the warden said. "Their objective was for us to go with them to meetings with the local people in order to convince them to support Soco's activities and show they had the full support of the ICCN."

Soco struck a deal with the Worldwide Fund for Nature to halt its exploration of the UNESCO World Heritage site after weeks of allegations of intimidation against environmentalists, including the shooting of the park's Belgian director, seriously wounding him.

Both the firm and Atalia deny allegations of corruption and of issuing threats.

Created in 1925 during Belgian colonial rule, Virunga park covers nearly 800,000 hectares (2.0 million acres) along the border with Uganda and Rwanda.