Extension works for the 67-meter-high launch tower was completed in Tongchang-ri, reported Xinhua citing South Korea`s Yonhap News Agency.
With the extension, the North Korea was estimated to be able to fire long-range rockets twice the size of Unha-3, which was fired into space in December 2012, two months before the country`s third nuclear test.
North Korea is likely to use the new launch tower to fire a longer-range rocket than the Unha-3 around the 70th anniversary of the founding of the Workers` Party of Korea on October 10, a government official was quoted as saying.
Signs of producing longer-range rockets were detected at an arms factory near Pyongyang, another official was quoted as saying.
South Korea maintains that UN Security Council resolutions have banned all launches based on North Korea`s ballistic missile technology.
