The statement was a signal to Iran and North Korea, which have been accused of pursuing controversial nuclear programs.
"The proliferation of weapons of mass destruction (WMD) and their means of delivery, together with international terrorism remain the pre-eminent threat to international peace and security," G8 leaders said in a statement, and called on the rest of the world to act together to deal with the challenge and avert the threat.
The leaders reaffirmed their resolve to take joint efforts to combat WMD proliferation and prevent them from falling into hands of terrorists.
G8 leaders also called on other countries that are not party to the Nuclear Nonproliferation Treaty to join them.
"We call on all states not Party to the Treaty on the Non-proliferation of Nuclear Weapons (NPT), the Chemical Weapons Convention (CWC), the Biological and Toxin Weapons Convention (BTWC) and the 1925 Geneva Protocol to accede to them without delay and those states that have not yet done so to subscribe to the Hague Code of Conduct Against Ballistic Missile Proliferation," the statement said.
G8 leaders also confirmed their commitment to allocate $20 billion until 2012 for the Global Partnership against the Spread of Weapons and Materials of Mass Destruction, which was launched in 2002 and is designed to "support specific cooperation projects, initially in Russia, to address non-proliferation, disarmament, counter-terrorism and nuclear safety issues."
The priorities of the program include destroying chemical weapons, dismantling decommissioned nuclear submarines, and disposing of fissile materials, and preventing terrorists from getting hold of WMD.
The G8 leaders thanked other nations outside the G8 that had signed up to the initiative.
"We appreciate the contribution of 13 non-G8 states who joined the Global Partnership," they said in the statement.