By Tom Burgis in Lagos, Financial Times, 30 Jan 2010A militant group in Nigeria’s conflict-torn oil province on Friday night called off its ceasefire, threatening to wreck an uneasy truce that had seen output start to recover in Africa’s biggest energy producer.The Movement for the Emancipation of the Niger Delta, a loose confederation of rebel organisations, echoed sentiments expressed by many former combatants in the delta, who say the government has failed to honour pledges that accompanied an amnesty declared in the middle of last year.