ABUJA, June 19 (Reuters) - Rebels from Nigeria's oil-producing Niger Delta on Thursday warned oil and gas tankers to avoid the region or stand the risk of being attacked. The rebel Movement for the Emancipation of the Niger Delta (MEND) said in an emailed statement it may conduct further attacks on oil facilities after gunmen caused the shutdown of production at Royal Dutch Shell's <RDSa.L> Bonga offshore oilfield earlier on Thursday. (Reporting by Randy Fabi; Editing by James Jukwey)
