( Reuters ) - A powerful Nigerian armed group threatened in an e-mail to the media on Sunday to resume attacks on oil facilities and kidnapping of foreigners, ending a four-month ceasefire.
The threat to disrupt oil supplies from Africa's top producer follows the arrest of a factional leader of the Movement for the Emancipation of the Niger Delta (MEND), Henry Okah, in Angola on arms trafficking charges on September 3.
"With effect from 12 midnight today, Sunday September 23, 2007, we will commence attacks on installations and abduction of expatriates," MEND said in an e-mailed statement.
MEND bombed oil facilities and abducted foreign workers in the southern delta from late 2005 to May this year, when President Umaru Yar'Adua took office promising to solve the crisis.
Since last year dozens of troops, militants and civilians have been killed, thousands of foreign workers have left and oil output from the world's eighth largest exporter has been cut by a fifth, raising world prices.
MEND, which says it is fighting against decades of neglect and marginalization of Nigeria's oil heartland, has mostly observed a ceasefire since May to allow for talks with the government.
But Okah has refused to sign up fully to the process and his associates in the underworld of the delta's largest city, Port Harcourt, last month engaged rival gangs and troops in street battles.
The e-mail accused the Nigerian government of trying to divide and rule the inhabitants of the delta, and attempting to bribe militants and leaders from the region.
"We will not sit back and allow our birthright to be exchanged for a bowl of porridge," the e-mail said.
The e-mail was signed "Jomo Gbomo" and sent from an address used by MEND for the past two years to communicate with the media. Security sources believe Okah and Gbomo are the same person, but Sunday's e-mail denied this.
Okah's wife told Reuters on Saturday that she suspected the Nigerian government was behind his detention in Angola and that Abuja was trying to weaken him.
The Niger Delta is home to all of Nigeria's oil, responsible for 95 percent of its hard currency earnings, but most people there live in poverty.
MEND's main demand is for the delta region to control its oil resources and pay tax to the federal government. But the line between ideological struggle and crime is blurred.
Corrupt officials in the region siphon off millions of dollars destined for basic services and development, and many are also involved in a big trade in crude oil stolen from pipelines crossing the region, civil society groups say.