US President Donald Trump has said he is not worried about Beijing's military drills around Taiwan which see Chinese forces practising a blockade of the island.

I have a great relationship with President Xi [Jinping], and he hasn't told me anything about [the drills]. I certainly have seen it, Trump told reporters at a press conference on Monday.

No, nothing worries me. They've been doing naval exercises for 20 years in that area, he said.

The two-day war games, which kicked off on Monday, take place nearly two weeks after the US announced one of its largest-ever arms sale to Taiwan. The sale had angered Beijing, which sees the self-governed island as a breakaway province.

The war games, which simulate the seizure and blockade of the island's key areas, are a warning against Taiwan independence separatist forces and external interference, the Chinese military said.

China's military exercises on Tuesday will see it run 10 hours of live-firing exercises in the sea and airspace of five locations surrounding the island.

Its Eastern Theater Command in charge of the Taiwan Strait said it has lined up destroyers, frigates and fighter-bombers to test the military's sea-air coordination and integrated containment capabilities.

Taiwan's defence ministry said it detected 130 Chinese military aircraft around the island on Tuesday morning, 90 of which crossed the median line - an unofficial border dividing China and Taiwan, the validity of which China has rejected.

The Taiwanese ministry also said it spotted more than a dozen Chinese navy vessels near the island. Taiwan's armed forces monitored the situation and have deployed aircraft, ships and coastal missile systems in response, the ministry said.

Taiwan's presidential office has criticised the drills, calling them a challenge to international norms.

In a Tuesday morning statement on social media, Taiwanese president Lai Ching-te said the Chinese Communist Party's escalation of military pressure was not something that a responsible power should do.

We will act responsibly and not escalate conflict or stir up disputes, he said, adding that Taiwan's military and national security team would do their best to ensure the safety of the country.

The main audience for this week's drills really is the United States, Donald Trump and Japan more than the people of Taiwan, Susan Shirk, former US Deputy Assistant Secretary of State, told the BBC's Newsday programme.

China has long vowed to reunify with Taiwan and has not ruled out the use of force to take it. It has ramped up pressure over Taipei with military drills and incursions into its waters and airspace. While Trump has downplayed Beijing's ongoing drills, his administration had recently announced a $11bn weapons package to Taiwan, which includes advanced rocket launchers and missiles.

The US has formal ties with Beijing rather than Taiwan, balancing diplomatic relations for decades while remaining a significant ally of Taiwan and its primary arms supplier.