The 14-billion-yen (118-million-dollar) satellite was launched on the ninth domestically-produced H-2A rocket at 3:27 pm (0627 GMT) from the Tanegashima Space Center in southern Japan.

Prime Minister Junichiro Koizumi hailed the second consecutive successful satellite launch in less than a month.

"This shows that the credibility of the H-2A rocket has firmly increased and that our country's space exploration is making steady progress," he said in a statement.

The rocket was carrying a 4.6-tonne payload -- the heaviest satellite ever launched by Japan -- that will control air traffic and serve as a backup for a weather satellite currently in use.

"The rocket continued to cruise smoothly ... We confirmed the successful separation (of the satellite) at 3:55 pm (0655 GMT)," an official at the Japan Aerospace Exploration Agency (JAXA) said.

JAXA last successfully put into orbit a land observation satellite using its H-2A rocket on January 24 and is due to launch an astronomical satellite on a mid-sized M-5 rocket on Tuesday.

Mitsubishi Heavy Industries, a heavyweight in Japanese industry, was the main builder of the H-2A rocket as part of a government privatization drive.

Pressure has mounted on Japanese officials in a space race with China as Beijing presses ahead in space and established countries take the lead in the satellite market.

The H-2A rocket suffered a setback in November 2003 after five successful launches. Ground controllers had to destroy the sixth rocket carrying a spy satellite to monitor North Korea just 10 minutes after lift-off when one of two rocket boosters failed to separate.

The 2003 failure was all the more embarrassing as it came one month after China became the third country after the United States and the former Soviet Union to launch a successful manned space flight.

Japan in February 2005 successfully launched a seventh H-2A rocket with a satellite to forecast weather.

But the space agency admitted a new setback in December when it said a Japanese spacecraft likely failed on its landmark mission to collect samples from an asteroid on its first attempt.

The six-meter (20-foot) Hayabusa spacecraft, which in November approached the asteroid 290 million kilometers (180 million miles) from Earth, went out of control because of a gas burst caused by leaking fuel.

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