China heaped praise on Wednesday on three African countries that refused to let Taiwan President Lai Ching-te's aircraft fly over their territories, forcing him to cancel a trip to Eswatini, while Taipei denounced their "servitude" to Beijing.

It is the first instance of a Taiwan president having to cancel a foreign trip due to denial of airspace access, as China steps up efforts to stifle the island's attempts at building diplomatic ties.

Lai had been due to leave for the small southern African kingdom, one of just 12 countries with diplomatic ties to Chinese-claimed Taiwan, but the previous night, Taiwan said his visit had to be delayed.

Taiwan said Seychelles, Mauritius, and Madagascar had revoked permission for Lai's aircraft to fly over their territories.

Lai said China had used economic "coercion" to get their cooperation - a claim denied by a spokesperson for China's Taiwan Affairs Office.

Zhang Han, the spokesperson, expressed appreciation for the position and "practice" of the three countries in adhering to the one-China principle.

"A just cause enjoys abundant support, while an unjust cause finds little support," he told a regular news conference in Beijing, quoting the ancient Chinese philosopher Mencius.

China views democratically-governed Taiwan as its territory despite Taipei's rejection of the claim, and frequently calls the issue a "red line" in its diplomatic relations with other countries.

In a separate statement, China's foreign ministry said it was clear there was "no longer a so-called Republic of China president in the world anymore", referring to Taiwan by its formal name.

"Anyone who wears that false title is acting against history and will only invite disgrace upon themselves," it said.

Madagascar and the Seychelles said they took the decision because they do not recognise Taiwan.

The cancellation of the Taiwan president's visit did not alter Eswatini's longstanding two-way ties with the island, said acting government spokesperson Thabile Mdluli.

"As a sovereign nation, Eswatini continues to pursue an independent and principled foreign policy that prioritises peace, cooperation and mutually beneficial partnerships with all members of the international community," Mdluli added.

TAIWAN CONDEMNS CHINA

China has a special dislike of Lai, whom it calls a "separatist". He rejects Beijing's sovereignty claims and says Taiwan has a right to engage with the rest of the world.

Taiwan has condemned China's actions.

On Wednesday, its foreign ministry described the comments by Seychelles and Madagascar as being "in servitude of China".

"The Republic of China is a sovereign state with the right to engage with the world — a right that cannot be denied, and that no country has the standing to obstruct," it added in a statement.

Though the US State Department has yet to comment, several US lawmakers expressed concern.

"This is not diplomacy; it is economic pressure aimed at isolating a democratic partner," the US House Select Committee on China wrote on X.

The move comes a little more than a week after China rolled out new incentives for Taiwan, including the easing of food imports, after opposition leader Cheng Li-wun, chairwoman of the Kuomintang (KMT), met President Xi Jinping in Beijing.

The KMT, which is often at odds with Lai's government, called on China to exercise restraint and give Taiwan sufficient diplomatic space.

"I think mainland China's pressure is not clever, especially after the Cheng-Xi meeting," senior KMT lawmaker Lai Shyh-bao told reporters in Taipei.