The United States and 10 of its allies will press on with plans to intercept vessels suspected of carrying weapons of mass destruction despite a warning from China that the move could be illegal.
The group aims to stop the proliferation of WMD
The agreement, reached in Paris, endorses the American Proliferation Security Initiative (PSI), which President George W Bush announced earlier this year.
The initiative is designed to halt the spread of weapons.
The 11 countries have agreed to board ships, force planes to land and inspect cargoes if they suspect that chemical, nuclear or biological weapons are being transported.
They are to hold a series of 10 joint exercises, starting next week in the western Pacific, involving ships from the US, Australia, Japan and France, to simulate an interception.
They will also try to recruit new members to the group and are due to meet in London next month.
China has criticised the initiative, arguing that it could contravene international law.
"The best way to prevent proliferation of weapons of mass destruction is through dialogue," a Chinese foreign ministry said.
"We understand the concerns of some countries about the proliferation of weapons of mass destruction... But many countries still question the efficiency and legitimacy of adopting this kind of measure."
In response to criticisms, the head of the American delegation says the group could seek to get approval for its actions from the UN Security Council if they feel there are areas where they do not have the proper authority.
"What we intend to do is consistent with national and
international authorities," John Bolton, undersecretary of state for arms control and international security, said after the group held talks in Paris.
North Korea concern
The group says new and stronger actions are required by the international community due to the increasingly aggressive efforts by "proliferators... to profit from the trade".
Although the PSI effort is not officially aimed at any one nation, Mr Bolton acknowledged that North Korea's nuclear weapons programme was a top concern, the Associated Press news agency reports.
In December last year, Spain intercepted a North Korean ship carrying Scud missiles and handed over the vessel to the United States.
Yemen later said it had ordered the missiles
and Washington allowed the ship to go after concluding the shipment did not break any laws.