MANILA (Reuters) - Filipino lawyers on Thursday announced a broad alliance to challenge President Rodrigo Duterte s 16-month war on drugs amid unprecedented scrutiny of the campaign in which more than 3,900 mostly urban, poor Filipinos have been killed. Police say the deaths were in self-defense after armed suspects resisted arrest. Critics dispute that and say executions are taking place, with zero accountability. Lawyers Against Extrajudicial Killings adds to a growing number of voices calling on the government to end the campaign.  It is the duty of all lawyers to consistently, uncompromisingly uphold and defend human rights,  said Edre Olalia, head of the National Union of People s Lawyers and one of the group s organizers.  Duterte s spokesman, Harry Roque, a congressman and human rights lawyer, denied rights violations on the part of the president but welcomed the new group.   Unless we can come up with actual evidence that there are extra-legal killings, then we cannot overcome the presumption (of regularity in the discharge of official functions),  Roque said.  He (Duterte) will not tolerate murders. He will only tolerate killings when it is in line with duty and when the engagement is legal,  Roque, who had prosecuted on behalf of murdered journalists, told reporters.  