President Tsai Ing-wen attended a ceremony for the first public flight of the "Brave Eagle" Advanced Jet Trainer (AJT), describing it as a "historic moment".

"Today is a big day for the Republic of China air force and it's also an important landmark for the domestic aerospace industry," Tsai told a crowd in central Taichung, using Taiwan's official name.

"This is a critical part of realising our defence self-sufficiency."

Trainers are what pilots learn on before switching to much more expensive fighter jets and the AJT will allow Taiwan to replace its current fleet of obsolete aircraft.

Democratic Taiwan lives with the constant threat of invasion by China which views the self-ruled island as part of its territory and has vowed to one day seize it, by force if necessary.

In recent decades it has found itself out-numbered and out-gunned by China's enormous People's Liberation Army.

The imbalance has been compounded by western governments becoming increasingly wary of selling it advanced weapon systems, fearful of incurring Beijing's wrath.

That has pushed Taiwan to develop its own hardware, including advanced missiles, boats and the new trainer jet.

Beijing has ramped up military, diplomatic and economic pressure since Tsai first took office in 2016 as she has refused to acknowledge that Taiwan is part of "one China".

She won a landslide reelection in January in what was seen as a strong rebuke to China's hardline campaign against the island.

The unveiling of the AJT comes as Taiwan's ageing fleet of fighter jets are being scrambled at an unprecedented rate.

Chinese jets have entered into Taiwan's air defence identification zone seven times in the last two weeks, according to Taipei's defence ministry.

The island currently has some 300 fighter jets, all in service since the 1990s, including US-made F-16s, French-made Mirage 2000-5s and the locally developed Indigenous Defensive Fighters.

The United States has remained Taiwan's leading unofficial ally and arms supplier, but until recently Taiwan had struggled to buy new fighter jets.

Since the election of US President Donald Trump, Washington has been more willing to sell big ticket items.

Last year the Trump administration announced it would sell 66 latest generation F-16 jets to Taiwan shortly after another huge military hardware sale including missiles and armoured vehicles.

The announcement infuriated Beijing, which vowed to sanction companies involved in the sale if it went through.