Xi Jinping issued a stark warning to visiting US president Donald Trump as they began their landmark summit on Thursday, saying that mishandling of the Taiwan issue could lead to “clashes or even conflict”, describing it as “an extremely dangerous situation”.

The warning came during closed-door talks on the first day of Mr Trump’s visit, the first by an American leader in nine years. The summit was intended to stabilise ties between the world’s two biggest powers amid mounting geopolitical tensions.

The Chinese president welcomed Mr Trump with lavish diplomatic pageantry but his warning was a stark reminder that the issue of Taiwan, a self-governing island claimed by China as a breakaway province, remained a major irritant in bilateral relations.

According to state media, Mr Xi presented his country’s claim to Taiwan as the biggest issue in US-China relations, telling Mr Trump that if the Taiwan issue was “handled well”, US-China relations could maintain “overall stability”, but failure to do so would place the relationship in “great jeopardy”.

Analysts had predicted Taiwan could emerge as the most sensitive issue at the summit for China, with many regarding it as the biggest potential obstacle to a broader US–China rapprochement. Beijing entered the talks hoping to secure concessions from Mr Trump on Taiwan, particularly around American arms sales, diplomatic language and official engagement with Taipei.

Conceding ground on Taiwan after consultation with Beijing would represent a departure from US policy on the self-governing island that has been in place since the presidency of Ronald Reagan.

In response to the summit in Beijing, Taiwanese government spokesperson Michelle Lee claimed on Thursday that China’s military threat was “the sole source ​of insecurity in the Taiwan Strait and the broader Indo-Pacific region”.

"Continuously strengthening national defence and effective collective deterrence is the single most critical factor in ensuring regional peace and stability," she added.

The Chinese hosts kicked off the two-day summit on Thursday with pomp and pageantry as Mr Xi greeted Mr Trump on the red carpet of Beijing’s Great Hall of the People, with the leaders shaking hands and smiling warmly.

They walked side by side past an honour guard and lines of cheering children as “The Star-Spangled Banner”, the American anthem, rang out across the square, accompanied by a 21-gun salute echoing through Tiananmen Square. Mr Trump was also seen occasionally patting Xi on the back during the ceremony.

Inside the Great Hall, the leaders delivered televised opening remarks and hailed the US-China relationship.

Mr Xi called for the two nations to be “partners not rivals” and to work together to confront an increasingly “complex and turbulent world”.

“Our two countries have more common interests than differences. Success in one is an opportunity for the other, and a stable bilateral relationship is good for the world. China and the US both stand to gain from cooperation and not lose from confrontation,” Mr Xi said.

Mr Trump played up his personal relationship with Mr Xi in his remarks and said they had been talking on the phone to iron out differences.

“It’s an honour to be with you. It’s an honour to be your friend and the relationship between China and the USA is going to be better than ever before,” the American leader said. "You and I have known each other now for a long time. In fact, the longest relationship of our two countries that any president has had, and that's to me, an honour. We've had a fantastic relationship. We've gotten along. When there were difficulties, we worked it out."

But those warm scenes were in stark contrast to the Chinese media reports of Xi’s Taiwan remarks, and the issue continued to raise its head after the two-hour bilateral talks were over, as the two leaders travelled to the Temple of Heaven, a 15th-century shrine symbolising the connection between heaven and earth.

Mr Trump’s travelling press pool repeatedly asked if they had discussed the Taiwan issue but the US president appeared to dodge the questions. He replied “great” when asked how the talks were going.

Asked about Taiwan specifically, he continued his previous thought. “Great place, incredible, China’s beautiful,” he said.

Asked again if he had talked about Taiwan, Mr Trump simply looked straight ahead, as did Mr Xi, and again ignored the question for the third time.

Mr Trump’s press pool was delayed for nearly 30 minutes after Chinese security officials objected to an armed Secret Service agent entering the Temple of Heaven compound. The standoff was resolved after discussions between US and Chinese officials, according to a pool report.

State broadcaster CCTV said that Mr Xi and Mr Trump exchanged views on a range of major global issues, including the Middle East crisis, the war in Ukraine, and tensions on the Korean peninsula.

On trade, Mr Xi said that economic and trade teams from both sides “produced generally balanced and positive outcomes”, which was a “good news for the people of the two countries and the world”, Xinhua reported

He told Mr Trump that trade wars had no winners.

"Where disagreements and frictions exist, equal-footed consultation is the only right choice," he said, urging the two sides to jointly sustain the good momentum that had worked hard to create.