The satellites were placed into initial parking orbit about 500 kilometers (300 miles) above the earth some 20 minutes after the US-made rocket blasted off over the weekend, Taiwan's National Space Organization (NSPO) said in a statement.

It will take 13 months for all the satellites, each of which weigh 62 kilograms (136 pounds), to settle in their designed orbital planes of about 700-800 kilometers. They are designed to have a lifespan of more than five years.

The aim is to "obtain the near-real time global distribution of air pressure, temperature, and water vapor of the atmosphere as well as the electron density of the ionosphere," the statement said.

"The data collected are used for weather prediction simulations, global climate-change analysis, and ionosphere and gravity research."

Taiwan, usually hit by typhoons in summer, has paid about 80 percent of the cost of the 100 million US dollar project, called FORMOSAT-3 here and COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate) in the United States.

The satellites were built and tested in Taiwan, NSPO officials said.

Taiwan launched its second satellite dubbed ROCSAT-2 in May 2004 as part of a 15-year space programme lunched in October 1991 at an estimated cost of 19.6 billion dollars (603.07 million US).

Though designed for scientific research, the French-made ROCSAT-2 satellite can take high-resolution pictures which can be used in different fields including for military purposes, Chen Cheng-hsing, who oversees the ROCSAT-2 satellite programme, has said.

Military analysts said that without a fully-controlled spy satellite, Taiwan would be unable to set up an anti-missile system while rival China increases the deployment of ballistic missiles targeting the island.

China views Taiwan as part of its territory awaiting reunification, by force if necessary.

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