He collaborated with Abdus Salam very closely at both scientific and humanitarian level since his student days at Imperial College. He joined the International Centre for Theoretical Physics(ICTP) in 1988 as Research Physicist and Coordinator of the High energy Section. Previously he had been at the Department of Theoretical Physics, University of Zurich. In 1994, he was designated as Head of the High Energy Group at ICTP. In August 2005, he was promoted to assistant director of ICTP. Since April 2011, he served as the Acting Deputy Director until his retirement on 31 December 2015.