Sept 30 (Reuters) - The United Nations on Thursday condemned the killing of Rohingya refugee leader Mohib Ullah and called on Bangladeshi authorities to investigate and hold the perpetrators of his shooting on Wednesday night accountable, U.N. spokesperson Stephanie Tremblay told a press briefing on Thursday. Mohib Ullah, who was in his late 40s, led one of the largest of several community groups to emerge since more than 730,000 Rohingya Muslims fled Myanmar after a military crackdown in August 2017. read more