The United Nations is nearing agreement on a treaty to regulate the $70bn global conventional arms trade.
The world body's 193 member states received the last revision of the draft treaty ahead of the final day of the drafting conference on Thursday.
Delegates and arms groups say India or Iran could still block the agreement.
UN member states began meeting last week in a final push to end years of discussions and hammer out a binding international treaty to end the lack of regulation over cross-border conventional arms sales.
"India, Syria and Iran are countries that could still cause trouble," a European diplomat speaking on condition of anonymity told the Reuters news agency. "But I'll wager the treaty will pass by consensus."
Iran, currently under a UN arms embargo over its nuclear programme, is eager to ensure its arms imports and exports are not curtailed, diplomats told Reuters.
Syria is in a two-year-old civil war and hopes Russian and Iranian arms keep flowing in, they added. But they are all under pressure to back the draft, envoys said.
"We are continuing to review the text with an eye toward ensuring that it accomplishes all of our goals, including that
it protect the sovereign right of states to conduct legitimate arms trade and, of course, that it not infringe upon the
constitutional right of our citizens to bear arms," a US representative told Reuters.
The National Rifle Association, a powerful US pro-gun lobbying group, opposes the treaty and has vowed to fight to prevent its ratification if it reaches Washington. The NRA says the treaty would undermine domestic gun-ownership rights.
The American Bar Association, an attorneys' lobby group, has said that the treaty would not impact the right to bear arms.
Ambassador Joanne Adamson, chief British delegate, said the new draft treaty has many improvements over earlier drafts.
"These [improvements] include inclusion of ammunition in the scope of the treaty, a new article on preventing diversion of arms, and strengthened section on exports which are prohibited," she said. "Human rights are at the heart of this text."
Several human rights groups and arms control advocates, including Amnesty International, Oxfam and Control Arms, praised the new draft.
They said despite shortcomings, it was a major improvement over an earlier draft that had too many loopholes.
"While there are still deficiencies in this final draft, this treaty has the potential to provide significant human rights protection and curb armed conflict and violence if all governments demonstrate the political will to implement it,"
Brian Wood of Amnesty International said.
But he made clear that there were problems with the text, including an overly narrow scope of types of arms covered.
It covers tanks, armoured combat vehicles, large-calibre artillery systems, combat aircraft, attack helicopters, warships, missiles and missile launchers and small arms and light arms.
The highly controversial predator drones and grenades are among the weapon categories that are not covered explicitly in the draft treaty.
Rights groups complained about one possible loophole in the current draft involving defence cooperation agreements.
Several diplomats who also oppose this loophole said it could exempt certain weapons transfers from the treaty.
Three delegates dubbed that provision the "India clause", because it was something India pushed hard for, they said.
Arms control campaigners and human rights groups say one person dies every minute worldwide as a result of armed violence and a treaty is needed to halt the uncontrolled flow of arms and ammunition they say fuels wars, atrocities and rights abuses.