"Shortly after the launch, we sent a destroy order to the rocket as we concluded that the mission cannot fulfill the purpose," said Shoko Yamamoto, a spokesman for the satellite launch project.

"We cannot tell further details, but at least we can say this mission ended in failure," Yamamoto said.

Television footage showed a Japanese H-2A rocket with the two spy satellites lifting off smoothly from a launch site on the southern island of Tanegashima some 1,000 kilometers (620 miles) southwest of Tokyo at 1:33 pm (0433 GMT).

But the governmental Japan Aerospace Exploration Agency's Tanegashima Space Center decided to destroy the rocket and the satellites about 10 minutes later due to troubles in the rocket, officials said.

According to the agency, one of the two rocket boosters failed to separate from the fuselage in the second phase of the flight.

"If we continue, it lacks speed and lowers its flight altitude," the agency said in a statement, adding that the destroy order was made based on the booster failure.

It was Japan's first launch failure since 1999 when it also destroyed a satellite rocket while in flight.

They had been scheduled to join another pair of spy satellites, which were launched in March in a 250 billion yen (2.3 billion dollar) government project to put four spy satellites into full operation this year.

The launch of the second pair, originally set for September 10, had been delayed by prolonged preparations and replacement of parts. It was further pushed back after trouble occurred in the H-2A rocket hours before its lift-off on September 27.

The latest failure was a sharp contrast to China's success in sending a Chinese astronaut into orbit to circle the Earth 14 times in a 21-hour flight.

The failure also overshadowed Japan's space programme and its ambitious satellite defence, observers said, adding that Japan will be forced to delay a planned launch of another H-2A rocket in February with a satellite to be used for weather observation.

"It was extremely regrettable as we have needed to strengthen our ability to collect intelligence," Prime Minister Junichiro Koizumi said in a statement.

"We will consider our future action while pursuing investigation into the cause immediately, strictly and thoroughly."

North Korea denounced the deployment of the first two satellites as a "hostile act", which could trigger a renewed arms race.

The satellite project was intended as a response to North Korea's firing of a suspected Taepodong ballistic missile over Japan into the Pacific in August 1998, a move that sent shockwaves around the region.

The launch came at a sensitive time for Japan and North Korea as the two countries prepared to sit down at six-way talks to resolve the crisis over Pyongyang's nuclear ambitions.

Some 400 police were around the launch site and coast guard ships were patrolling waters to thwart possible terrorist attacks or any attempt by North Korea to disrupt the launch, angry at what it sees as threatening re-militarisation by Japan.

Long under the US security umbrella during the Cold War years, Japan was awakened to the need for self-defence following a series of North Korea's missile tests.

SPACE.WIRE