Seoul, March 7 (DPA) North Korea warned Sunday that South Korea's planned military exercises with the United States would force it to build up its nuclear defences and reverse the process of denuclearisation of the Korean peninsula.

'The military exercises are virtually nuclear war games. In response, we, North Korea, will bolster our nuclear deterrent for self-defence,' the North's official KCNA news agency quoted a senior military official as saying.

The annual exercises, due to take place from Monday until March 18, involve 10,000 US troops stationed in South Korea as well as 8,000 from abroad.

North Korea also said it no longer felt bound by the armistice agreement that ended the 1950-53 Korean War.

The comments come days after the China's chief nuclear envoy, Wu Dawei, said North Korea would return to disarmament talks the North stormed out of in April 2009 in protest at UN sanctions.

Military analysts said the military exercises gave North Korea an excuse to temporarily shelve Chinese-led diplomatic efforts to restart the six-nation nuclear disarmament negotiations.

'The exercises would put a brake on on-going efforts to restart the talks. But once the drills are over, the diplomatic drive will resume to restart the talks,' said Chang Yong Seok, a senior researcher at the Institute for Peace Affairs.

The North conducted a second nuclear test last May after it tested its first atomic bomb in 2006, triggering strict UN sanctions.

The North routinely blasts the annual military exercises as preparations for invading the North, despite assurances from Washington and Seoul that they are purely defensive.