Major powers haggled 'word by word' at the UN Monday over a treaty on the $70 billion a year conventional arms trade, amid calls from governments and activists to speed up talks to meet a looming deadline.

With the negotiating conference set to end on Friday, the 193 UN member states still do not have a draft text to send back to governments for approval, according to diplomats.

On current estimates the draft will not be ready until Wednesday, giving governments two days to consider what would be a major international treaty.

Disagreements remain between the main arms producers -- the United States, Russia, China, Britain, Germany and France -- on the scope of the treaty and even the criteria for how to judge an arms transfer.

A group of countries led by Syria, North Korea, Iran and Cuba have sought from the start to emasculate the proposed treaty, diplomats and activists say.

"Time for the negotiations is running out," warned Britain's Foreign Office Minister Alistair Burt and International Development Minister Alan Duncan in a joint statement.

"Genuine differences remain to be bridged and there is a small but determined minority of states who oppose the treaty.

"Their opposition is directly counter to the interests of the vast majority of the world's population," the two British ministers added.

Most of the talks in the three week old negotiations are now behind closed doors, said Anna Macdonald, the Oxfam charity's arms control expert.

"The president of the conference is running through a draft text literally word by word in closed session," Macdonald told reporters.

Since the start, the United States has opposed the inclusion of ammunition, China does not want small arms and both Russia and China have sought restrictions on references to humanitarian law.

But pressure for an accord has increased with a statement by 74 African, Latin American and European countries which said there must be a halt to arms transfers where "there is a substantial risk that those transfers will be used in violation of humanitarian law," Macdonald said.

The 74 also insisted that small arms and ammunition be included.

"The large majority of states do want a positive outcome," said Macdonald.

None of the main arms producers signed the statement.

According to Brian Wood, Amnesty International's arms control expert, a US decision on how far to agree on the criteria for triggering the halt of an arms transfer for humanitarian reasons will be crucial.

Wood said the decision will have to be taken by President Barack Obama.

"They are talking about balance and say they want to balance national security considerations with the other criteria," said Wood.

"If they create an opt-out for national security, everybody knows that a lot of governments will use that a lot of the time to just make irresponsible arms transfers," he added.

The treaty must be agreed by consensus so any of the 193 countries involved could object on Friday. And even if a treaty is concluded, the conference has not yet decided how many countries must ratify it to bring it into force.