AFRICAN peace envoys have met Ethiopian Prime Minister Abiy Ahmed, a day after he said the military was beginning the "final phase" of an offensive in the northern Tigray region that rights groups fear could bring huge civilian casualties. The government had given the Tigray People's Liberation Front (TPLF) until Wednesday to lay down their arms or face an assault on Mekelle, the regional capital of 500,000 people. The United Nations says 200 aid workers are also in the city. The African Union envoys were in Addis Ababa "with a view to helping to mediate between the parties to the…