He said the preparations are "now making brisk headway" at the Tonghae Satellite Launching Ground in Hwadae County, located in North Hamgyong Province, in the country's northeast.
The area is widely believed to be the launch site for the North's Taepodong-2 rocket, the longest-range missile in its arsenal.
Military analysts believe North Korea has more than 1,000 missiles of various ranges, including:
Rodong - estimated range 1,400km; can strike anywhere in South Korea
Taepodong 1– estimated range 2,500km; thought to be the type shot over Japan in 1998
Taepodong-2 - estimated range of 6,700km; believed to be able to reach US military bases in Japan, Guam and even parts of Alaska.
Taepodong-2 missile was test-fired into sea of Japan in July 2006, sparking international condemnation. But US and South Korea say test was unsuccessful.
The announcement comes despite US warnings that it would be "very unhelpful" for the North to proceed with any missile test.
North Korea said last week that it had the right to "space development".
When it test-fired the shorter-range Taepodong-1 missile over Japan in 1998, North Korea claimed to have put a satellite into orbit.
Some intelligence reports from outside North Korea have since pointed to evidence that that rocket may indeed have been carrying a satellite, but that it failed to reach orbit.
The Taepodong-2, North Korea's most advanced missile with an estimated range of 6,700km, is thought to be capable of hitting Japan and even parts of Alaska.
With modifications, analysts say, it could also hit the US west coast, although it has never successfully flown.
An attempt to fire the Taepodong-2 was last made in 2006. Pyongyang acknowledged it was a missile launch, but it failed about 40 seconds after blast-off.
On Monday South Korea's military said the North "recently" deployed a new, shorter range missile that could hit the US military outpost on the Pacific island of Guam, the northern tip of Australia, much of Russia and India.
A South Korea defence ministry report released on Monday also claimed the North was "presumed" to have secured about 40kg of nuclear bomb-making plutonium from reprocessing spent nuclear fuel rods from its Yongbyon reactor.
|Protesters in South Korea have denounced the planned launch [Reuters]
Pyongyang carried out its first nuclear test in October 2006, but most analysts believe it is still some time away from developing a nuclear warhead able to fit on a missile.
Nonetheless, the US has put pressure on the North to scrap plans to launch the Taepodong-2.
Hillary Clinton, who visited the North's neighbours South Korea and Japan last week on her first foreign tour as US secretary of state, warned Pyongyang against any missile test, saying any such move "would be very unhelpful in moving our relationship forward".
The intense speculation over the possible test launch has also unnerved North Korea's neighbours.
Japan has said it is ready for any possible emergency, and was considering "appropriate measures" in case of a launch.
"The government always considers taking appropriate measures to prepare for any emergency situations," Yasuhisa Kawamura, deputy press secretary of the foreign ministry, told the AFP news agency.
"The government is now analysing and examining a variety of information," he said, refusing to comment on whether Japanese intelligence believes a launch is imminent.
China, North Korea's closest ally, says it has taken note of the planned launch, but refused to comment further.
"China takes note of this matter," foreign ministry spokesman Ma Zhaoxu told reporters on Tuesday.
"We hope relevant parties can contribute to peace and stability on the Korean peninsula and the rest of the region."