By Felix Onuah
ABUJA (Reuters) - Nigerian President Muhammadu Buhari has canceled at the last minute a visit planned for Thursday to the oil-producing Niger Delta that has been rocked by a spate of militant attacks.
Vice President Yemi Osinbajo visited the restive region in Buhari's place to launch a cleanup program in an area badly hit by oil spills, and said the government was working with community leaders to end militant attacks on oil installations.
No reason has been given for Buhari's cancellation.
"We are determined to put right the wrongs of the past, where the people of this land were treated unfairly and the environment unduly polluted and degraded," Osinbajo said in a speech to launch the program in the Ogoniland area.
"The cleanup of this land will require change on the part of all those who deal with the Niger Delta environment - particularly the oil companies and our communities."
The southern Delta swamps, where most of Nigeria's crude is extracted, have been targeted a series of militant attacks on oil and gas pipelines which have driven down the country's oil output to a 20-year low.
Buhari's visit would have been the first by the former military ruler to the Delta since taking office in May last year. Critics have accused Buhari, a Muslim from the north, of neglecting the predominantly Christian south.
Last month he skipped a visit to the commercial capital Lagos, in the south, again at the last minute. Posters with his photograph had been already hung up to welcome the president, before his spokesman cited "scheduling" difficulties.
Hours after the announcement of Buhari's visit to the swamps on Tuesday, the Niger Delta Avengers militant group, which has claimed several attacks on Chevron and Royal Dutch Shell facilities, issued a warning to oil firms that their "facilities and personnel will bear the brunt of our fury".
The Avengers have accused Buhari of ignoring local problems.
Buhari said on Sunday the government would hold talks with Delta community leaders to address their grievances. Residents have for years complained about oil industry pollution and about being economically marginalized by government policy.
Achim Steiner, the U.N. Environment Programme (UNEP) executive director who joined Osinbajo the ceremony, said the cleanup "cannot happen overnight" but he hoped the government, oil firms and locals could work together to reduce pollution.
Local officials and Western allies such as Britain have told Buhari that moving army reinforcements into the Delta region would not be enough to stop the attacks and that the population's grievances must be tackled.
(Additional reporting by Seun Sanni, in Lagos; Writing by Ulf Laessing and Alexis Akwagyiram; Editing by Mark Heinrich)