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

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, worth 9.8 billion yen (90 million dollars), about 10 minutes later after 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.

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

The satellites had been scheduled to join another pair 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 in sharp contrast to China's success last month in sending a Chinese astronaut into orbit to circle the Earth 14 times in a 21-hour flight.

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, observers said.

"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 an 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.

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

SPACE.WIRE