North Korea says its ruling party has approved what it calls "overwhelming and offensive countermeasures" against its enemies, reiterating its confrontational stance towards the United States and South Korea.

The state-run Korean Central Television reported on Monday that the Central Committee of the Workers' Party discussed nuclear and missile development during a three-day plenary meeting that ended on Sunday.

The broadcaster said the committee affirmed the politburo's policy of increasing the production of powerful nuclear weapons.

It condemned Washington and Seoul for conducting military exercises, and said the members approved concrete plans and modes of action to implement overwhelming and offensive countermeasures.

The broadcaster did not elaborate, but South Korea's Yonhap news agency reports that Pyongyang may conduct missile and nuclear tests in response to joint drills by the US, South Korea and Japan.

The participants of the meeting also reportedly agreed to strengthen solidarity with the countries that oppose what they call the US strategy for world supremacy, apparently alluding to China and Russia.