Trump wrapped up a state visit to Beijing on Friday where Chinese President Xi Jinping had pressed him not to support Taiwan, which China claims is part of its territory.

Taiwan depends heavily on US security backing to deter China from carrying out its threat to annex the island by force.

Taiwan "is a sovereign and independent democratic nation, and is not subordinate to the People's Republic of China", Taiwan's foreign ministry said in a statement.

The ministry also insisted that US arms sales were part of Washington's security commitment to Taiwan, after Trump flagged that he was considering the issue.

Taiwan's statements came after Trump issued a warning to the island against making a declaration of independence.

"I'm not looking to have somebody go independent. And, you know, we're supposed to travel 9,500 miles to fight a war. I'm not looking for that," he told Fox News' "Special Report with Bret Baier".

The United States recognises only Beijing and does not support formal independence by Taiwan, but historically has stopped short of explicitly saying it opposes independence.

Under US law, the United States is required to provide weapons to Taiwan for its defence, but it has been ambiguous on whether US forces would come to the island's aid.

Xi had begun the summit with a warning on Taiwan, whose President Lai Ching-te considers the island already independent, making a declaration unnecessary.

The Chinese leader told Trump that missteps on the sensitive issue could cause "conflict".

Ahead of the summit, Trump had said he would speak to Xi about US arms sales to Taiwan, a departure from Washington's previous insistence that it would not consult Beijing on the matter.

Taiwan's parliament recently approved a $25 billion defence spending bill that will be used for US weapons.

Speaking to reporters on Friday en route to Washington, Trump said: "I'll make a determination over the next fairly short period of time."

Taiwan's foreign ministry said Saturday that arms were "not only a US security commitment to Taiwan clearly stipulated in the Taiwan Relations Act, but also a form of joint deterrence against regional threats".

China has sworn to take the island and has not ruled out using force, ramping up military pressure in recent years.