China claims self-ruled Taiwan is part of its territory and opposes the democratic island's participation in international organisations and exchanges with other countries.

The minister of Taiwan's Ocean Affairs Council, Kuan Bi-ling, said in a Facebook post on Tuesday that Kenyan authorities had detained two of its delegates to the Our Ocean Conference in the city of Mombasa this week.

Foreign Minister Lin Chia-lung said on Wednesday that Kenya had done so under "high-level Chinese pressure".

"We see this is a new normal. China is pressuring other countries more and more to behave towards Taiwan in a way that exceeds the past."

Taiwan had been invited to the forum and had paid to set up a booth, Lin said.

But Kenya had "distorted" its interpretation of the One China principle, "expanding it limitlessly to block our people from participating", he told reporters in the capital Taipei.

"This is absolutely wrong and we strongly protest it."

In recent years, China has increased military activity around Taiwan while also seeking to peel off its few remaining formal diplomatic allies.

Kuan said in her post that the two delegates were detained "for an extended period", their passports and phones were confiscated, and they "faced a situation close to deportation".

Others had their entry permits revoked, she said.

"This is not diplomatic coldness, it is unfair treatment", she wrote.