British Prime Minister Tony Blair said on Monday that the nuclear test by the Democratic People's Republic of Korea (DPRK) was an "irresponsible act."

"I condemn this completely irresponsible act by the government of the DPRK," Blair said.

"This further act of defiance shows DPRK's disregard for the concerns of its neighbors and the wider international community and contravenes DPRK's commitments under the Non-Proliferation Treaty and UN Security Council Resolution 1695," Blair added.

On Monday, DPRK's official Korean Central News Agency announced that the country had conducted an underground nuclear test successfully.