TAIPEI (AFP) - Taiwan plans to test-fire its newest anti-missile system for the first time in the United States next month as relations with rival China deteriorate, a defence source and media reports said on Monday (June 27).

Relations between China and Taiwan have cooled rapidly under the island's new Beijing-sceptic President Tsai Ing-wen, who took office in May, ending an eight-year rapprochement.

The test of the US-made Patriot Advanced Capability-3 (PAC-3) system will be launched at the White Sands Missile Range, New Mexico, in early July, a Defence Ministry source told AFP, in a move likely to irk Beijing even though it was arranged before Ms Tsai took the helm.

According to the source, the test will be conducted in the US to avoid China collecting information about it, and due to space restrictions in Taiwan.

The American Institute in Taiwan, the de facto US embassy, would not comment on the test, which was also reported in Taiwan's Liberty Times newspaper.

Despite having no official diplomatic ties with Taipei after recognising Beijing in 1979, the US is still Taiwan's greatest ally and main arms supplier.

The missile system was purchased in 2008, well before Ms Tsai's leadership, and the test was approved by the US last year, according to the Liberty Times.

Taiwan bought three earlier model PAC-2 systems in the 1990s and also tested them in the US. They were deployed in the densely populated greater Taipei area.

It then bought the new PAC-3 - a system designed to intercept incoming ballistic missiles near the end of their trajectory - as part of a US$6.5 billion arms sale by the US in 2008, which infuriated Beijing at the time.

The system is already partly operational and will shield Taipei, as well as central Taichung and southern Kaohsiung from any Chinese missile attacks, according to the defence ministry.

The Taiwanese missile unit involved in the July drill will fire two missiles to intercept a missile launched by the US military, which simulates an incoming Chinese ballistic missile, the Liberty Times reported.

Japan has also tested the PAC-3 on US soil.

In the latest setback for cross-strait ties, China said on Sunday that communications with Taiwan had been suspended after the island's new government failed to acknowledge the concept that there is only "one China".

China still insists self-ruling Taiwan is part of its territory awaiting reunification, by force if necessary, even though the two sides split in 1949 after a civil war.

According to Taiwan's defence ministry there are 1,500 Chinese missiles aimed at the island.

China launched ballistic missiles into waters off Taiwan in 1995 and 1996 in an attempt to deter voters in the island's first democratic presidential elections.