TAIPEI - China must rethink its hardline stance towards Taiwan, President Tsai Ing-wen said Wednesday, as she warned the island was already independent and that any invasion would be "very costly" for Beijing.

Tsai won a second term over the weekend with a record 8.2 million votes, an outcome that was seen as a forceful rebuke of China's ongoing campaign to isolate the self-ruled island.

China's leadership had made no secret of its desire to see Tsai turfed out because she and her party refuse to acknowledge their view that the island is part of a "one China".

Beijing regards Taiwan as its territory and has vowed to one day seize it, by force if necessary -- especially if it declares independence.

But in her first interview since Saturday's re-election, Tsai told the BBC there was no need to formally announce independence because the island already runs itself.

"We don't have a need to declare ourselves an independent state," she said in the interview, which aired on Wednesday.

"We are an independent country already and we call ourselves the Republic of China, Taiwan."

Modern Taiwan has been run separately from the mainland for the last 70 years.

For decades, it was a dictatorship under Chiang Kai-shek's nationalists following their 1949 defeat to the communists in China's civil war.

But since the 1980s, it has morphed into one of Asia's most progressive democracies, although it is only diplomatically recognized by a dwindling handful of countries.

Polls show growing numbers of Taiwanese reject the idea that the island should be part of the Chinese mainland.

"We have a separate identity and we're a country of our own," Tsai said. "We deserve respect from China". -AFP