Nigerian militants said Saturday they had carried out their first attack on an oil pipeline since an amnesty offer because the absence of President Umaru Yar'Adua was delaying peace talks. The Movement for the Emancipation of the Niger Delta said its fighters, armed with rocket launchers and machineguns, carried out a “warning strike” against a Royal Dutch Shell or Chevron pipeline in Abonemma, Rivers state. There was no independent confirmation. A spokesman for the military joint taskforce, Lieut. Col. Timothy Antigha, said he was making checks and had no immediate comment. Shell had no immediate comment. Security contractors working in the oil industry said they had received no reports of a pipeline attack. If confirmed, the strike would be a major blow to peace efforts by Yar'Adua's administration, which has pledged to spend billions of dollars developing the region after thousands of gunmen accepted a presidential amnesty which ended in October.