More than $900bn is spent each year on arms, Oxfam says

At Labour's conference, Mr Straw condemned the "vile, lethal trade" in small arms in Africa and elsewhere.

Charities have hailed his pledge as the biggest move on the issue for decades as Britain is the first major nation to make the move.

As well as defending Iraq policy, Mr Straw also praised the Muslim faith.

'Stop divisions'

Pointing to the global terror threat, he said people had tried to hijack different religions to justify their violence throughout human history.

Islam preached tolerance, peace and equality, argued Mr Straw.

"It is up to all of us - Christian, Hindu, Jew, Muslim or Sikh - any religion or no religion to ensure that these blasphemous men of violence succeed neither in their carnage nor in their wider agenda of dividing our communities one from another," he said.

Mr Straw said there was no greater challenge than ending the Israeli-Palestinian conflict.

He urged the Palestinian Authority to get serious on reining in terror groups while Israel had to stop targeted killings and end settlement building in the West Bank and the routing of the security barrier onto Palestinian land.

The minister also said Britain had a moral duty to respond to the Sudan crisis and was leading peace efforts and he attacked Tory claims over the proposed European constitution as false.

Arms menace

But it was his promise on the arms trade which pleased campaigners who have complained there are currently no legally binding international arms export controls.

Mr Straw told delegates: "In Sudan, as elsewhere, the carnage and the terror is carried out not by sophisticated high-tech weapons but by so-called small arms - rifles, revolvers, machine guns, mortars.

"In Europe we now have a comprehensive arms control code of practice. But this is not the same across the world.

"Greater international action is therefore needed to tackle the plague of small arms in Africa and elsewhere.

"I am therefore pleased to tell this conference that we will start work soon with international partners, drawing on experience from the EU, to build support for an international arms trade treaty further to extend the international rule of law."

Leadership role

Oxfam policy director Justin Forsyth said: "Straw's support for the arms trade treaty brings tough international arms controls much closer.

"People we work with whose lives have been ruined by the unregulated trade in weapons will at last be able to see the light at the end of the tunnel.

"The UK, the second largest exporter of weapons, can play a vital role in keeping weapons out of the wrong hands and making people safe from arms violence.

"It must now show global leadership and help make this treaty a reality."

Liberal Democrat foreign affairs spokesman Sir Menzies Campbell welcomed any attempt to control the spread of small arms.

"But for any such agreement to be effective, it will require the active participation, support and agreement of the US, which in the past has shown itself to be reluctant to sign up to such a treaty," he said.

Quentin Williamson, for the UK Independence Party, said: "Anything which stops the proliferation of lethal weapons is to be welcomed providing that it is done even handedly."