Francis is UNESCO Chair of African Peace and Conflict Studies in the Department of Peace Studies at the University of Bradford.

UNESCO: Professor David J. Francis

But Professor Paul Rogers, of the University of Bradford's department of peace studies, said white phosphorus could be considered a chemical weapon if deliberately aimed at people.

BBC: NEWS | Middle East | Iraq probes US phosphorus weapons

Dr Shaun Gregory is reader in international security at the University of Bradford and has been researching the risks of nuclear war between India and Pakistan in Islamabad and Delhi for the last three years.

BBC: Analysis: South Asia's nuclear brinksmanship