China is holding military drills around Taiwan simulating the seizure and blockade of the island's key areas, as a warning against separatist forces.

The army, navy, air force and rocket force have been dispatched for the drills which include live-fire exercises, the Chinese military said.

Codenamed Justice Mission 2025, the drills are taking place days after the US announced the sale of one of its largest weapons packages to Taiwan worth $11bn (£8.2bn). That move drew sharp protest from Beijing which in turn sanctioned US defence firms.

Taiwan's push to ramp up its defence this year has also angered Beijing, which claims the self-ruled island as its territory.

Taiwan's presidential office has criticised the upcoming Chinese drills, calling them a challenge to international norms. Its defence ministry said it had detected 89 Chinese military aircraft and 28 warships and coastguard vessels near Taiwan on Monday.

The ministry said separately it had deployed its own missile systems and forces to monitor the situation, adding they are on high alert to defend Taiwan and protect our people.

In a post on Weibo, the Chinese military's Eastern Theater Command - in charge of the Taiwan Strait - described the upcoming military exercise as a shield of justice.

All those plotting independence will be annihilated upon encountering the shield! the post read.

While some initial drills have begun, the military said it would conduct a major exercise from 08:00 to 18:00 local time on Tuesday.

Beijing's foreign ministry called the drills a severe punishment for separatist forces seeking independence through force and warned external forces against using Taiwan to contain China.

Any sinister schemes to obstruct China's reunification are doomed to fail, the ministry's spokesman Lin Jian said at a regular press briefing on Monday.

While China has long called for the peaceful reunification with Taiwan, it also has a law stating it will resort to non-peaceful means to prevent the island's secession.

Beijing has accused Taiwan's president Lai Ching-te of pursuing Taiwan independence. The president maintains Taiwan is already a sovereign nation and therefore has no need to formally declare independence.

On Sunday, Lai said in a local television interview that Taiwan needed to keep raising the difficulty so [China] can never meet the standard for an invasion.

He also said that his administration was committed to maintaining the status quo and would not provoke China - though he added that peace relies on real strength.

Polls consistently show that most Taiwanese people want the status quo, meaning they neither want to unify with China, nor to formally declare independence.

The drills this week in the Taiwan Strait aim at deterrence outside the island chain, China's military said. China's ties with Japan have plunged to their iciest in years after Japanese leader Sanae Takaichi suggested last month - in response to a question asked in parliament - that Japan's self-defence forces could step in if China attacked Taiwan.

Taiwan's transport ministry has said both international and domestic flights will be diverted away from dangerous areas as the drills continue, affecting more than 100,000 passengers.