North Korean space program official Paek Chunghou told reporters assembled at the country's General Satellite Control and Command Center several miles northwest of Pyongyang the satellite had been placed on the rocket and fuel was being injected into the rocket, China's official Xinhua News Agency reported.
"We're sure that we will be successful," he said.
Asked if the launch would take place Thursday, when weather conditions are expected to be very good, he answered that the exact time of the launch had not yet been determined.
The Korean Times said a government source said the North was expected to launch the rocket Saturday, the day before a military parade celebrating the centenary of the nation's founder, Kim Il Sung, though a Thursday or Friday launch was possible depending on weather conditions.
The United States and other nations have been trying to get the North to call off the launch, which they fear is a cover for development of an intercontinental ballistic missile that could carry a nuclear warhead.
The Chosun Ilbo reported experts said it will take just 10 minutes to determine whether the rocket launch is successful once it is ignited. One rocket expert told the newspaper this version of the North Korean rocket likely has a more advanced propulsion system than one fired in 2009.
The North's official Korean Central News Agency said North Korea's new leader Kim Jong Un, grandson of the country's founder, was given the newly-created title of "first secretary" of the ruling Workers' Party, Yonhap News Agency reported Wednesday. Kim's late father, Kim Jong II, was named "eternal" general secretary of the ruling party.
Yonhap said Korea watchers had been waiting to see if the new leader would be given his father's title.
Kim Jong-gak, a senior military officer, has been named as the North's new defense chief, Yonhap said.