Washington  - The United States urged North Korea to stop issuing threats and instead to return to negotiations following a warning from Pyongyang that it would test a nuclear device and ballistic missiles.

North Korea said it wanted an immediate apology from the UN Security Council in return for standing down on the plans to conduct the tests.

State Department acting spokesman Robert Wood said North Korea's threats would only result in further isolation, and said Pyongyang should come back to the six-nation disarmament negotiations it abandoned after the Security Council statement.

"I don't think you'll see an apology from the Security Council," Wood said.

North Korea said it will restart its nuclear programme for self- defence after pulling out of the six-nation talks that produced a North Korean agreement in 2007 to denuclearize in return for aid and improving diplomatic relations.

"Unless the UN Security Council offers an apology immediately, we will be forced to take additional self-defence measures to protect the highest interests of our republic," a Foreign Ministry spokesman said in a statement cited by the state-run Korean Central News Agency. (dpa)