Taiwan's navy will arm its submarines with anti-ship missiles for the first time ever beginning next year, a report said Wednesday, as the island boosts its defence capabilities against rival China.

The Taipei-based United Daily News said the navy, which ordered the US-built Harpoon missiles in 2008, recently test-fired the weapons in the United States, in preparation for installing them on its two Dutch-built submarines.

"The missiles will become operational on the two submarines next year," the newspaper said, citing an unnamed naval source.

It said that the more than 30 missiles, which have a range of 120 kilometres (72 miles), will give the two submarines long-distance strike capabilities that they have previously lacked.

Taiwan's navy declined to comment on the report, citing a long-standing policy of not discussing arms purchases with the media.

Taiwan, which already has Harpoons installed on frigates and F-16 fighter jets, ordered the submarine-launched missiles in 2008 as part of a $6.5 billion arms sale that sparked strong protests from Beijing.

The deal also included advanced interceptor Patriot missiles and Apache attack helicopters.

Ties between Taipei and Beijing have improved markedly since Ma Ying-jeou of the China-friendly Kuomintang party came to power in 2008 promising to boost trade links and allow more Chinese tourists to visit the island.

But Beijing still sees the island as part of its territory awaiting reunification, by force if necessary, even though Taiwan has governed itself since 1949 at the end of a civil war.

China has repeatedly threatened to invade Taiwan should the island declare formal independence, prompting Taipei to seek more advanced weapons, largely from the United States.