Militants in Nigeria's Niger Delta yesterday said they had blown up two major oil pipelines belonging to Royal Dutch Shell, forcing the firm to halt some production and helping push world oil prices higher.

The Movement for the Emancipation of the Niger Delta (MEND), whose campaign of violence has cut Nigeria's oil output by around a fifth since early 2006, said its members conducted the attacks early yesterday.

"Detonation engineers backed by heavily armed fighters... sabotaged two major pipelines in Rivers state of Nigeria," it said in an e-mailed statement.

The group said the two pipelines were attacked at Kula - through which the Nembe Creek trunkline passes - and at Rumuekpe, located around 50 kilometres west of the main oil city of Port Harcourt.

Shell, which operates onshore in Nigeria in a joint venture with state oil firm NNPC, said it had halted some output from the Nembe Creek trunkline but gave no details on the volume.

Oil Minister Odein Ajumogobia said Shell was still assessing the damage and any supposed figures for the amount of production shut down would be "speculative".

Industry sources said about 130,000 barrels per day of crude oil flows through the Nembe Creek pipeline, while some 100,000 bpd passes through Rumuekpe. Both pipelines are connected to the Bonny export terminal in Nigeria, the world's eighth largest exporter.

US crude oil prices found support from the news, trading above $123 a barrel yesterday.