A plan to extend compulsory military service in Taiwan to one year from the current four months will be announced on Tuesday, a senior government official said, as the island deals with rising Chinese military pressure.

The office of Taiwan President Tsai Ing-wen said she will call a national security meeting on Tuesday morning to discuss reinforcing the island's civil defence, followed by a news conference on unspecified new civil defence measures.

Tsai's security team, including high-level officials from the defence ministry and the National Security Council, has been reviewing Taiwan's military system since 2020 amid increasing threats from China, according to the official.

Taipei, which rejects Beijing's sovereignty claims, on Monday reported the largest-ever Chinese air force incursion into the island's air defence identification zone, with 43 Chinese planes crossing an unofficial buffer between the two sides.

China also staged war games near Taiwan in August following a visit to Taipei by then-U.S. House Speaker Nancy Pelosi.

"China's various unilateral behaviours have become a major concern for regional security," said the official, who took part in the high-level security discussion and declined to be named.

Under the plans due to come into effect in 2024, conscripts would undergo more intense training, including shooting exercises and combat instruction used by U.S. forces, the official said.

Conscripts would be tasked with guarding key infrastructure, enabling regular forces to respond more swiftly in the event of any attempt by China to invade, they added.

Taiwan's defence ministry declined to comment.

Tsai is overseeing a broad modernisation programme, championing the idea of "asymmetric warfare" to make the island's forces more mobile, agile and harder to attack.

The official Central News Agency, citing government and ruling party sources familiar with the matter, first reported late on Monday that Taiwan's government would be announcing its plan to extend compulsory military service.

Taiwan has been gradually shifting from a conscript military to a volunteer-dominated professional force, but China's growing assertiveness towards the island it claims as its own, as well as Russia's invasion of Ukraine, have prompted debate about how to boost defence. Russia calls the war a "special operation".

Previous governments under the ruling Democratic Progressive Party and the main opposition Kuomintang cut compulsory service for men from more than two years to four months to please younger voters as tensions had eased between Taipei and Beijing.

Reuters has reported that military training in Taiwan, particularly for conscripts and reservists, had deteriorated.

In recent years, China has stepped up diplomatic, military and economic pressure on the self-governed island to accept Beijing's rule. Taiwan's government says only Taiwanese people can decide their future and vows to defend itself if attacked. (Reporting By Yimou Lee and Ben Blanchard. Editing by Gerry Doyle & Simon Cameron-Moore)