Britain is hopeful the United Nations Security Council will deliver a resolution against North Korea that includes tougher financial sanctions, after the state's nuclear test last week.
Britain joined the United States, Australia and East Asian defence ministers in condemning North Korea's latest military moves at the Asia Security Conference in Singapore.
The US Defense Secretary Robert Gates warned that Washington would not accept a nuclear North Korea.
The US and Japan have circulated a draft UN Security Council resolution condemning the test and calling for enforcement of sanctions imposed after Pyongyang's first 2006 nuclear test, which included a widely ignored limited trade and arms embargo.
Britain says Chinese concern voiced at the forum gave hope that the UN resolution would bring "some concerted action".