Beijing has reacted furiously to a visit by US House Speaker Nancy Pelosi to Taiwan, which it claims as its territory and has vowed to retake -- by force if necessary.

It has since Thursday encircled the self-ruled, democratic island with a series of huge military drills that have been roundly condemned by the United States and other Western allies.

And Friday saw its foreign ministry hit back further against the United States, suspending talks and cooperation on multiple agreements between the two -- including on climate change.

The world's two largest polluters last year pledged to work together to accelerate climate action this decade, and vowed to meet regularly to "address the climate crisis".

But that deal looks shaky as relations sink to some of their lowest levels in years, as do agreements on everything from talks on military matters to anti-drug cooperation.

Pelosi -- who Beijing also hit with sanctions for the visit -- has defended her trip to Taiwan, saying Friday that Washington would "not allow" China to isolate the island.

In Washington, the White House summoned China's ambassador to Washington to condemn Beijing's "irresponsible" behaviour over Taiwan, a senior US official said Friday.

Taiwan has also condemned Beijing's response to the visit, with premier Su Tseng-chang calling for allies to push for de-escalation.

"(We) didn't expect that the evil neighbour next door would show off its power at our door and arbitrarily jeopardise the busiest waterways in the world with its military exercises," he told reporters.

- 'Our motherland is powerful' -

Beijing has said its military exercises will continue until midday Sunday, and Taipei reported that 68 Chinese planes and 13 warships crossed the "median line" that runs down the Taiwan Strait on Friday.

AFP journalists on the Chinese island of Pingtan saw a fighter jet flying overhead, prompting tourists to snap photos as it flew along the coast.

A Chinese military vessel sailing through the Taiwan Strait was also visible, they added.

China's drills involved a "conventional missile firepower assault" in waters to the east of Taiwan, the Chinese military said.

And state broadcaster CCTV reported that Chinese missiles had flown directly over Taiwan -- a major escalation if officially confirmed.

On the Chinese island of Pingtan, local tourists proudly extolled their country's military might against its much smaller neighbour.

"Our motherland is powerful. We are not afraid of having war with Taiwan, the US or any country in the world," Liu, a 40-year-old tourist from Zhejiang province, told AFP.

"We hope to unify Taiwan soon. We are not scared of anyone," he added.

"We don't want to start a war, but we are not afraid of others."

Wang, a businesswoman, was more sanguine about prospects for cross-strait ties.

"I hope China can unify Taiwan, but I don't want war," she said. "I hope this issue can be solved in a peaceful way."

- 'Significant escalation' -

The scale and intensity of China's drills have triggered outrage in the United States and other democracies.

"These provocative actions are a significant escalation," US Secretary of State Antony Blinken said after talks with Southeast Asian foreign ministers at an ASEAN summit in Phnom Penh.

"The fact is, the speaker's visit was peaceful. There is no justification for this extreme, disproportionate and escalatory military response," he added.

China's foreign minister countered with a warning for the United States, urging Washington not to escalate tensions.

"America's habit is to create a problem and then use this problem to achieve its goals. But this approach will not work with China," Wang Yi said at a press conference on the sidelines of the same summit.

"We want to issue a warning to the US not to act rashly and not to create a bigger crisis."

Japan has lodged a formal diplomatic complaint against Beijing, with five of China's missiles believed to have landed in its exclusive economic zone.

On Friday, Japan's foreign ministry said China "cancelled" a planned bilateral meeting on the sidelines of the ASEAN summit.

And Australia -- which has a troubled relationship with China, its largest trading partner -- condemned the drills as "disproportionate and destabilising".

The manoeuvres are taking place along some of the world's busiest shipping routes, used to disseminate the global supply of vital semiconductors and electronic equipment produced in East Asia.