South Korea will soon enter the second stage of its program to develop the country's own space vehicle by 2021, the government said Thursday.

The second, three-year stage of the rocket development plan will begin at the start of next month, in which the country will develop a 75-ton thrust engine, according to the Ministry of Science, ICT and Technology.

Following a successful development of a 75-ton thruster, the country will build a 300-ton booster, using four 75-ton thrust engines, which will be capable of sending a 1.5-ton satellite into space.

The 300-ton space rocket, named the Korea Space Launch Vehicle 2 (KSLV-II), will be test-fired during the third and final stage of the space program that will commence in April 2018.

The first stage of the 1.96 trillion-won ($1.68 billion) program began in March 2010, in which the country successfully built and test-fired a 7-ton thrust engine, the ministry said.

"We have achieved our main objectives of developing a 7-ton liquid engine and building an engine test facility under the first development stage, and we can now enter the second stage of the program to develop a 75-ton engine system and build a test launch vehicle," it said in a press release.

The country launched a Russian-made space rocket, the KSLV-I, in January 2013, becoming the world's 13th nation ever to have successfully sent a rocket into space from its own soil.

The KSLV-II is set to be test-fired in 2019, followed by an official launch in 2021. (Yonhap)