North Korea has said it will launch a long-range rocket in mid-December, a provocative move just eight months after a failed attempt violated a United Nations ban on further development of its nuclear and missile programmes.

The rocket launch is likely to heighten already strained tensions with Washington and Seoul, especially as South Korea will hold its presidential election on December 19. Neither will it please the single-party state's only ally, China.

"If North Korea does carry out a launch, Beijing will not be happy," said Evans Revere, a former senior US State Department official and expert on East Asia. "It flies in the face of China's request for North Korea to reduce tensions in the region and not escalate them."

The development is the latest example of the country's leader, Kim Jong Un, striking a newly aggressive pose to coincide with the anniversary of his father's death a year ago on December 17. Last week North Korea replaced its Defence Minister with Kim Kyok Sik, a hardline military commander believed to have been responsible for deadly attacks on South Korea in 2010.