An agreement, as proposed by Oxfam and other groups, to stop arms sales to rights violators will have implications for several Western nations. Britain and the United States, for example, have been criticised for arms sales to Saudi Arabia and Bahrain, Gulf states with poor human rights records.

AMMUNITION KEY

Speaking at an Oxfam event, photographer Paul Conroy, whose colleague Marie Colvin was killed when they were trapped by Syrian army shelling in the Baba Amr district of the Syrian city of Homs in February, said rules governing ammunition were key.

The United States, Syria and Egypt are among countries that have objected to the inclusion of ammunition controls in any global arms treaty, according to Oxfam.

“In (Baba Amr) I heard almost every type of heavy weapon .... The thing that struck me was the supply and rate of fire of the weapons. We are talking continuing fire of heavy weapons and a continual supply chain,” Conroy said.

Oxfam concedes there is a risk a strong arms treaty would alienate some countries, but said it would be difficult to later beef up a weak treaty and that a stronger pact from the outset would give rights groups “more backing” when protesting at some arms sales.

The U.N. Security Council’s five permanent members -- Britain, France, Russia, China and the United States, as well as Germany -- are among the world’s biggest weapons exporters.

Some argue that the weapons black market is a bigger problem than state-to-state sales. But Oxfam, part of a global Control Arms campaign for a “bullet-proof” treaty, said controls on state sales would stem the flow of arms to illicit vendors.