The announcement came after North Korea held a rare party conference widely expected to see more power formally transferred to Kim Jong-un.
The country is due to launch a rocket, set to go between Thursday and Monday.
North Korea says the rocket will put a satellite into orbit but the US says the launch is a disguised test of long-range missile technology.
The launch path will take the rocket south between the Philippines and Japan. Both South Korea and Japan have said that they will shoot it down if it threatens their territory.
End QuoteNorth Korea often looks like a place marooned, a survivor from an age when Soviet republics, with their strongmen rulers, were common”
The country's rubber-stamp parliament is also meeting on Friday and the two meetings have been seen as forums for advancing the transition of power to Kim Jong-un following the death of his father in December 2011.
Leadership titles: Who has what?
- Supreme Leader: Kim Jong-il, July 1994 to December 2011; Kim Jong-un, from December 2011
- Workers' Party: Kim Jong-il, General Secretary, October 1997 to December 2011 and Eternal General Secretary, from April 2012; Kim Jong-un, First Secretary, from April 2012
- Supreme Commander of the Korean People's Army: Kim Jong-il, December 1991 to December 2011; Kim Jong-un, from December 2011
- Chairman of the Central Military Commission of the Workers' Party: Kim Jong-il October 1997 to December 2011; Kim Jong-un, from April 2012
- Chairman of the National Defence Commission of North Korea: Kim Jong-il, from April 1993 to December 2011; (Kim Jong-un has yet to be given this title/position)
But critics say that the launch constitutes a test of long-range missile technology banned under UN resolutions.
The rocket is due to launch any day between 12 and 16 April from the Tongchang-ri site on the country's north-west coast.
A number of airlines have altered flight paths and the US has sent a ship-mounted radar to monitor the launch.
Japan said it was on alert ahead of the launch. "We want to be fully prepared for any possible contingency," Prime Minister Yoshihiko Noda said.
Pyongyang agreed in February to a partial freeze in nuclear activities and a missile test moratorium in return for US food aid. But that deal was put on hold last month after the North announced its rocket launch plans.