LONDON, July 11: Iraqi chemical weapons posed no significant risk to the world in the run-up to the US-led invasion to oust Saddam Hussein, the former head of an international arms non-proliferation agency said on Friday.

“Not really, no,” said Ron Manley, former director of verification at the Organization for the Prohibition of Chemical Weapons, when asked on BBC radio if Iraq’s suspected arsenal of chemical weapons had posed a threat before the invasion.

Mr Manley, who had first-hand experience in Iraq, said any agents produced before the start of UN weapons inspections in 1991 would be useless by now.

He also said there was no sign of the large factories necessary to produce chemical arms after UN weapons inspectors left Iraq in 1998.

“There were only two real scenarios which anyone considered — either there were weapons hidden from 1991 or they were manufacturing weapons after 1998,” Mr Manley said.

“If there were weapons from before 1991 hidden in Iraq, knowing what we know about Iraqi agents and the chemistry of their agents, these weapons would be useless by today because of decomposition,” he said.

“If they were manufacturing after 1998, then I think the question is where?”

“You can’t make chemical weapons of military significance in a small room. You need big chemical infrastructure, and that sort of infrastructure would be seen,” he said.

Mr Manley said he and other experts believed there was “no question” that the former Iraqi government had had a chemical weapons programme.

But he added: “My view at the start of the war was that there might have been a few odd weapons left over from previous times or they may have stored some material from which they could fill one or two rounds or a couple of missiles, but I don’t believe there was any significant stocks of materials.”