Australia, the US and Japan have described North Korea's latest nuclear test as a highly provocative act that undermines regional security and contravenes United Nations Security Council resolutions.

The joint announcement came during the fifth Security and Defence Cooperation Forum (SDCF) plenary session held in Washington DC on Wednesday, where officials from the three nations discussed trilateral political-military defence co-operation in areas such as humanitarian assistance and disaster relief, regional capacity development, maritime security, and the state of regional security affairs.

"The three delegations discussed the recent North Korean nuclear test," a statement released by the US State Department said.

"They agreed that this highly provocative act was a clear violation of UN Security Council resolutions ... as well as North Korea's own commitments under the September 19, 2005 joint statement of the six-party talks.

"The three delegations further affirmed that North Korea's actions undermine regional security, increase the risks of proliferation, and further isolate it from the international community."

US assistant secretary of state Andrew Shapiro and assistant secretary of Defence Mark Lippert co-chaired the forum.

In defiance of UN Security Council resolutions, the latest issued last month, North Korea on Tuesday detonated a nuclear device at a remote underground site.

It is seen as a key step toward its goal of building a bomb small enough to be fitted on a missile capable of striking the United States.