WASHINGTON, March 31: The Pentagon said on Wednesday it planned to sell Taiwan long-range "early warning" radar equipment worth as much as $1.78 billion, a deal bound to anger China at a tense time in cross-straits relations.

The planned sale "will contribute to the foreign policy and national security of the United States by helping to improve the security and defensive capability of the recipient, which has been and continues to be an important force for economic progress in the Far East," the Pentagon's Defence Security and Cooperation Agency said in a statement.

The radars will boost Taiwan's ability to "identify and detect ballistic missiles, cruise missiles and air-breathing target threats", said the statement, sent to the US Congress on Tuesday and made public on Wednesday.

Air breathing target threats are weapons systems that operate in the Earth's atmosphere, as opposed to space. The sale has been in the works since 1999, when it was approved in principle by the administration of former president Bill Clinton, said Shirley Kan, an expert on US arms sales to Taiwan at the research arm of the Library of Congress.

The United States has pledged to help Taiwan defend itself against a Chinese attack. China threatened to intervene after President Chen Shui-bian recently won a second four-year term in an election that faces an opposition challenge.

Shirley Kan said the announcement followed approval in November by the defence committee of Taiwan's parliament of funding for the ultra High Frequency long-range radars.

A Taiwan official said he expected a contract for the work to be awarded soon. Raytheon Co. and Lockheed Martin Corp are the two largest US companies expected to bid for the project, the Pentagon said. -Reuters