The two-day war games code-named "Justice Mission 2025" have been slammed by Taipei as "highly provocative and reckless".

China claims Taiwan as part of its sovereign territory and has refused to rule out military action to seize the island democracy.

AFP journalists in Pingtan -- a Chinese island at the closest point to Taiwan's main island -- saw a volley of rockets blast into the air at around 9:00 am (0100 GMT) on Tuesday, leaving trails of white smoke.

At least 10 were launched in quick succession, sending a booming sound reverberating across the sky and drawing tourists towards the seafront to snap photos and videos on their phones.

China's People's Liberation Army (PLA) said in a statement shortly afterwards that it had "conducted long-range live fire drills in the waters to the north of the Taiwan Island and achieved desired effects".

The show of force follows a bumper round of arms sales to Taipei by the United States -- Taiwan's main security backer -- and comments from Japan's prime minister that the use of force against Taiwan could warrant a military response from Tokyo.

China's top diplomat Wang Yi said Tuesday that Beijing would "forcefully counter" large-scale US weapons sales to Taiwan, adding that any attempt to obstruct China's unification with the island "will inevitably end in failure".

Foreign ministry spokesman Lin Jian called the drills a "punitive response to Taiwan independence separatist forces and a necessary action to defend national sovereignty and territorial integrity".

Taiwan's President Lai Ching-te expressed his "strongest condemnation" and said Beijing was "deliberately undermining regional stability through military intimidation".

"This is a blatant provocation against regional security and the international order," he wrote on Facebook, adding that Taipei would not escalate the situation.

- 'Live-fire training' -

China said on Tuesday morning that it had deployed destroyers, frigates, fighters and bombers "to conduct drills on subjects of identification and verification, warning and expulsion, simulated strikes, assault on maritime targets, as well as anti-air and anti-submarine operations".

A statement from the PLA's Eastern Theater Command said the exercises in the waters to the north and south of Taiwan "tested capabilities of sea-air coordination and integrated blockade and control".

State broadcaster CCTV reported that a core theme of the exercises was a "blockade" of key Taiwanese ports, including Keelung in the north and Kaohsiung in the south.

Chinese authorities published a map of five large zones around Taiwan where the war games would take place. They are due to finish at 6:00 pm on Tuesday.

Taiwan said the zones, some of which are within 12 nautical miles of its coast, had affected international shipping and aviation routes.

Dozens of flights to Taiwan's Kinmen and Matsu islands were cancelled, according to the island's Civil Aviation Administration, affecting around 6,000 passengers, while more than 850 scheduled international flights will be "affected" and could face delays.

Taiwan's defence ministry said on Tuesday it had detected 130 Chinese military aircraft near the island, as well as 14 Chinese navy ships and eight unspecified government vessels, in the 24 hours ending 6:00 am.

Taiwan's coast guard said it deployed 14 ships to monitor the naval activity, "employing a one-on-one shadowing approach to forcefully deter the vessels".

- Stoic reaction -

Many ordinary Taiwanese reacted stoically.

"There have been so many drills like this over the years that we are used to it," said fishmonger Chiang Sheng-ming, 24, at a market in the capital Taipei.

"If you stand your ground, there's nothing to be afraid of," added fruitseller Tseng Chang-chih, 80.

"War? Impossible. It's just posturing. If they really attacked Taiwan, they would have to pay a price."

China's military last held large-scale drills involving live firing around Taiwan in April -- surprise manoeuvres condemned by Taipei.

Beijing said this month it would take "resolute and forceful measures" to safeguard its territory after Taiwan said the United States had approved a major $11 billion arms sale.

US President Donald Trump said he was not concerned about the drills, appearing to brush aside the possibility of counterpart Xi Jinping ordering an invasion of Taiwan.

"I don't believe he's going to be doing it," Trump said.

burs-je/mjw