US satellite data indicates that North Korea appears to have begun fuelling a rocket it plans to launch this month in defiance of international opposition, a Japanese newspaper reported on Friday, citing a US defence official.

Pyongyang has announced it will launch a satellite-bearing rocket sometime between February 8-25, which is around the time of the birthday on February 16 of late leader Kim Jong-Il, father of current supremo Kim Jong-Un.

The North insists its space programme is purely scientific in nature, but the United States and allies, including South Korea, say its rocket launches are aimed at developing an inter-continental ballistic missile capable of striking the US mainland.

North Korea "will finish preparations for the launch as soon as the next several days", the US defense department official told the Asahi Shimbun, which did not provide the official's name.

Since Thursday, movement of people and equipment has become active around the launch pad and a fuel storehouse at North Korea's Dongchang-ri base in the country's northwest, the official said, according to the report datelined Washington.

The United States judged that the fuelling appears to have started as it has been monitoring Pyongyang's movements via military intelligence satellites which can analyse objects as small as 30 centimetres (12 inches), the report cited the official as saying.
Given the difficulty in stopping the process once fuelling begins, preparation work normally finishes within several days of that, the official told the Asahi.

Sanctions imposed by the United Nations prohibit North Korea from any use of ballistic missile technology, and such a launch would amount to another major violation of UN Security Council resolutions following its fourth nuclear test last month.