A United Nations committee has voted overwhelmingly to begin work on drawing up an international arms trade treaty.
Major arms manufacturers Russia and China abstained from the vote
The measure would close loopholes in existing laws which mean guns still end up in conflict zones despite arms embargoes and export controls.
It could also stop the supply of weapons to countries whose development is being hampered by arms spending.
Only the US - a major arms manufacturer - voted against the treaty, saying it wanted to rely on existing agreements.
A total of 139 states voted for the motion. There were 24 abstentions.
Major weapons manufacturers such as Britain, France and Germany voted to begin work on the treaty, as did major emerging arms exporters Bulgaria and Ukraine.
Russia and China, also major arms manufacturers, were among the countries to abstain.
UK Minister for International Development Gareth Thomas said an international treaty was the best way to curb the supply of weapons.
"All countries should support such a treaty as it offers the hope of a safer world where children are not scared to go to school," he said.
The UN secretary general has one year to produce a report on how to introduce common international standards for the import, export and transfer of conventional arms.
GLOBAL ARMS TRADE
Top 5 arms exporters: Russia, USA, UK, France and Germany account for about 80% of global arms exports
Global military spending: in excess of $1,000bn
Emerging exporters: Brazil, China, India, Israel, Pakistan
Top 5 arms importers: India, Saudi Arabia, Iraq, Turkey, Japan
The BBC's Laura Trevelyan at the UN says it could be years before an international arms trade treaty is actually agreed - but this vote is an important first step.
Globalisation has made existing export controls inadequate, our correspondent says - often, a weapons company with its headquarters in a country with strict export controls will manufacture components in nations with lax laws.
Some developing countries fear a treaty will just create a cartel or a suppliers' club for the major weapons exporters, our correspondent adds.
Human rights organisations have welcomed the move.
A new treaty would close loopholes in existing laws
Amnesty International described the vote as "an historic opportunity", saying "any credible treaty must outlaw those transfers, which fuel the systematic murder, rape, torture and expulsion of thousands of people".
One of those campaigning for the treaty was Richard Wilson, whose sister was taken from a bus and shot dead in 2000, while working in Burundi as a school teacher.
He told the BBC's World Today that the major arms exporting countries had to acknowledge their role in providing weapons to the poorest parts of the world.
"The attackers fired off nearly 1,000 rounds of ammunition. This is in the poorest country in the world.
"That says something about the easy availability of weapons, and anything that can be done to reduce that can help to prevent at least some of these tragedies in the future," he said.
Nobel peace prize winners, including Archbishop Desmond Tutu, have also backed the idea of such a treaty.
BBC defence and security correspondent Rob Watson says any eventual treaty faces many hurdles, including the question of how to stop those shady international arms dealers who are not in the habit of obtaining export licences?
Assurances will also need to be provided to arms exporters like Russia and China and emerging manufacturers that any treaty is not aimed at damaging their arms industries, our correspondent adds.