South Korean media say North Korea is making preparations to launch a second military satellite from a site in its northwestern region. Pyongyang says it successfully launched its first spy satellite in November.

The Yonhap News Agency on Thursday quoted South Korean military sources as saying that a covering was set up recently at the Sohae satellite launching station.

The report said the North is apparently preparing to launch another spy satellite because it set up a similar cover when assembling a rocket in the past. The cover is believed to have been used to avoid monitoring by US reconnaissance satellites.

The news agency also said it has been confirmed that a combustion test of an engine for a three-stage rocket has been carried out.

A spokesperson for South Korea's Joint Chiefs of Staff told a news conference on Thursday that while there are activities for an additional military satellite launch by the North, there are no signs of an imminent launch as of now.

North Korea's five-year defense program calls for operations of reconnaissance satellites. Following what it called a successful launch of the Malligyong-1 satellite in November, Pyongyang says it will launch three more this year.

South Korea plans to put its second reconnaissance satellite into orbit by using a US private-sector rocket in early April. A view is growing in the country that the North may go ahead with a second launch before then.