Abuja, Feb 16 : Nigerian President Muhammadu Buhari has congratulated Ngozi Okonjo-Iweala on her appointment as the director-general of the World Trade Organization (WTO). In a statement, Buhari voiced confidence that Okonjo-Iweala's track record of "integrity, diligence, and passion for development will continue to yield positive results and rewards to mankind" as she takes up another "onerous task of service to the world and humanity", Xinhua news agency reported. "Dr. Okonjo-Iweala, who over the years set major records of economic reforms in Nigeria as minister of finance, and later minister of foreign affairs, will excel in her new position and validate the global mandate of repositioning and strengthening the multilateral institution for the greater good of all," Buhari said on Monday. Members of the WTO on Monday agreed by consensus to appoint Okonjo-Iweala, a two-time former finance minister of Nigeria, as the next director-general, giving her the mandate to revitalize the 164-member global trade body. She is expected to fully take office on March 1. /IANS