South Korea's domestically assembled space rocket, which crashed after reaching the altitude of 70 km, might have exploded, Seoul's science minister Ahn Byung- man told reporters.

The two-stage satellite-carrier Naro-1, or the Korea Space Launch Vehicle-1 (KSLV-1), lifted off from the Naro Space Center in South Jeolla Province, about 485 kilometers south of Seoul, at 5:01 p.m. local time (0801 GMT), but communications with it was lost 137 seconds after the takeoff.

The minister offered an apology to the public over botching up the ambitious project, but said the country will continue its efforts to better the technology. South Korean and Russian experts will form a team to look into the cause of the failure.

The launch of the 140-ton rocket, made with the help of Russian experts, came a day after a technical problem with firefighting equipment delayed the initially planned blastoff. South Korea has put 502.5 billion won (404.5 million U.S. dollars) into developing the Naro-1.

Last year, a technical glitch botched up the first attempt at the rocket launch. A faulty fairing assembly prevented the rocket from putting the satellite into the orbit and the rocket veered off course.

With yet another failed attempt, South Korea has to put a brake on its ambition to join the ranks of a handful of other countries which have succeeded in putting a satellite into orbit using a locally assembled rocket.