David Cameron has welcomed a landmark deal regulating the international arms trade, saying it will "ease the immense human suffering" caused by conflicts.
The United Nations General Assembly resolution backing the arms trade treaty was overwhelmingly passed by a vote of 154 to three, with 23 abstentions.
The 193-member world body voted after Iran, North Korea and Syria blocked its adoption by consensus at a negotiating conference last Thursday. The three countries voted "no" on the resolution.
The vote capped a more than decade-long campaign by activists and some governments to regulate the global arms trade and try to keep illicit weapons out of the hands of terrorists, insurgent fighters and organized crime.
It will not control the domestic use of weapons in any country, but it will require countries to establish national regulations to control arms transfers.
It covers battle tanks, armoured combat vehicles, large-calibre artillery systems, combat aircraft, attack helicopters, warships, missiles and missile launchers, and small arms and light weapons.
Mr Cameron said: "This is a landmark agreement that will save lives and ease the immense human suffering caused by armed conflict around the world.
"It will reduce the number of illegal arms and make it harder for these to reach the hands of criminals and terrorists who are set on using them to destroy the lives of others.
"We should be proud of the role Britain has played to secure this ambitious agreement, working with international partners to secure this momentous step that will make our world safer for all."
The treaty will not control the domestic use of weapons in any country, but it will require countries to establish national regulations to control arms transfers.
The document covers battle tanks, armoured combat vehicles, large-calibre artillery systems, combat aircraft, attack helicopters, warships, missiles and missile launchers, small arms and light weapons.
Deputy Prime Minister Nick Clegg said he hoped that the treaty could be strengthened and expanded in future.
He said: "This treaty will bring much greater - and much needed - regulation to arms sales across the world and is a big step forward in clamping down on weapons going to rogue regimes and to the black market. It will save lives and help to combat terrorism.
"I recognise that many would like us to go further and I hope that the treaty agreed today is a baseline that can be expanded on and strengthened - and that more countries will endorse it - in the coming years."