International talks started Monday on a treaty to regulate the $70 billion a year global arms trade, with the Syria conflict and trafficking into Africa casting a shadow on efforts to secure an effective accord.

Negotiators from the 193 United Nations members have until July 27 to come up with a draft treaty. But most diplomats and observers say it will be a mammoth task to reach an accord.

The United States is by far the world's biggest arms trader, accounting for more than 40% of conventional weapons sales. Britain, China, France, Germany and Russia follow them.

All of the major producers have reasons to limit any treaty.

The United States -- which produces six billion bullets a year -- wants to exclude munitions, according to diplomats. China does not want the treaty to cover small arms, which it exports en masse to developing countries.

China, Russia and Arab countries say the accord's criteria are subjective and politically motivated.

The European nations say they want a treaty that at least makes the international trade more transparent.

Activist groups such as Oxfam and Amnesty International have highlighted the conflict in Syria and new areas of Africa as reasons for a tough treaty.

Ahead of the negotiations at UN headquarters, the foreign ministers of France, Britain and Germany and Sweden's trade minister called for a comprehensive treaty that will reduce what they called "a growing threat to humanity".

"Every year, millions of people around the world suffer from the direct and indirect effects of the poorly regulated arms trade and the illicit trafficking of arms," they wrote in the statement published in European newspapers.

The European ministers acknowledged that as leading exporters, their countries bear "a special responsibility in this matter."

They said any treaty should be legally binding, but nationally enforced.

"This will ensure the global consistency required to make the treaty effective, while maintaining state signatories' right to decide on arms transfers," they said.

The ministers also stated that they believed that the arms trade treaty should cover all types of conventional weapons, including small and light weapons, all munitions, and related technologies.

Brian Wood, Amnesty International's arms control chief activist, condemned the "completely irresponsible and reckless decision-making of the Russian government in supplying arms (to Syria) when they know they are going to be used for terrible violations and atrocities."

But Russia insists its arms supplies to Syria, its main Middle East ally, are legal and have no impact on the war in which activists say at least 15,800 people have died. China makes the same point about its deals in Africa.

Australia's Foreign Minister Bob Carr said that 2,000 people die each day because of illegally traded small weapons. "We want a strong and precise treaty that enables countries to track and report major arms transfers and sales," he told reporters.

"I think we can see today perhaps a sense of urgency today" on the arms trade treaty, said Finland's Foreign Minister Erkki Tuomioja.

"We see in many parts of the world, conflicts where small arms and light arms which may have been originally legally transferred have fallen into the hands of criminal groups or terrorist groups or other actors who use them indiscriminately."

He said "these weapons can be regarded as the real weapons of mass destruction."

If the negotiations produce an accord, the treaty could come into force in late 2013.

If the talks fail, a draft accord could still be taken to the 193-member UN General Assembly.