The rebels would be handed over after extradition processes were completed, Angolan President Eduardo Dos Santos told Nigerian President Umaru Yar'Adua at a meeting in Riyadh, the News Agency of Nigeria (NAN) said.

Henry Okah, factional leader of the Movement for the Emancipation of the Niger Delta (MEND), and an unidentified man, were arrested in September on arms trafficking charges. Nigeria had previously said it wanted the pair to face trial at home.

"We are trying to find a formula to resolve the issue which has nothing to do with politics but criminality; they are Nigerian citizens, so we cannot charge them in Angola," Dos Santos told Yar'Adua, the Nigerian president's office said in a statement.

"I assure you that we will ultimately release them to you for trial in Nigeria, but we must resolve the legal issues first," Dos Santos said.

Yar'Adua and Dos Santos, leaders of Africa's top oil producers, were in Riyadh for an OPEC meeting.

MEND has carried out a series of attacks and kidnappings on oil facilities since late 2005, prompting thousands of foreign workers to flee the southern delta which produces almost all of Nigeria's crude oil.

The group, which suspended attacks with the inauguration of Yar'Adua in May to allow the new government a chance to make peace, called off the ceasefire after the arrest of the pair, accusing Nigeria of masterminding it.

MEND has since claimed responsibility for four separate attacks on major oil facilities since October 20, including Thursday's attack on a pipeline that feeds the Forcados oil export terminal operated by Royal Dutch Shell.

MEND says it is fighting for access to oil revenues by impoverished local communities in the delta that have been neglected by successive corrupt Nigerian governments.