TAIPEI, Taiwan -- Pro-independence party candidate Tsai Ing-wen claimed victory in Taiwan's presidential election late Saturday to become the island's first female head of state.

The election took place amid concerns that Taiwan's economy is under threat from China and broad opposition to Beijing's demands for political unification.

Tsai said the election outcome was a further show of how ingrained democracy has become on the self-governing island. The results showed that Taiwanese people wish for a government "steadfast in protecting this nation's sovereignty," she said at her campaign headquarters.

By Saturday night, she had more than 56 per cent of votes counted, while the Nationalists' Eric Chu had 31 per cent, with a third-party candidate trailing in the distance.

Chu earlier conceded the massive loss and resigned from leadership of the China-friendly party that has governed Taiwan for eight years. Outgoing President Ma Ying-jeou is constitutionally barred from another term.

Tsai said one of her top priorities would be to unite Taiwan in order to gain strength and respect from international society. "Only when we grow stronger will we be able to gain respect and protect our people and our democratic way of life," Tsai said, referring to Taiwan by its official name, the Republic of China.

She said she would correct the policy mistakes of the past, but warned that: "The challenges that Taiwan faces will not disappear in one day."

Tsai pledged to maintain the "status quo of peace and stability" in relations with China. She said both sides have a responsibility to find a mutually acceptable means of interacting, while adding that Taiwan's international space must be respected. Provocations and pressure from China would destabilize relations, she said.

The newly election legislature will convene next month, while Tsai's inauguration is scheduled for May.

Addressing a thin crowd of a few hundred supporters at his campaign headquarters, the Nationalists' Chu said: "We failed. The Nationalist Party lost the elections. We didn't work hard enough." He followed his concession speech by making a long bow.

Reflecting unease over a slowdown in Taiwan's once-mighty economy, undeclared voter Hsieh Lee-fung said providing opportunities to the next generation was the most important issue.

"Economic progress is related closely to our leadership, like land reform and housing prices. People aren't making enough money to afford homes," Hsieh said.

Tsai has proposed to open 200,000 units of affordable housing in eight years. Her party suggested in May that Taiwan's laws change to raise wages and cut work weeks from 84 per two weeks to 40 in one.

Her win will introduce new uncertainty in the complicated relationship between Taiwan and mainland China, which claims the island as its own territory and threatens to use force if it declares formal independence.

"Taiwan and China need to keep some distance," said Willie Yao, a computer engineer voting in Taipei who said he backed Tsai. "The change of president would mean still letting Taiwanese make the decision."

Tsai has refused to endorse the principle that Taiwan and China are parts of a single nation to be unified eventually. Beijing has made that its baseline for continuing negotiations that have produced a series of pacts on trade, transport and exchanges.

Observers say China is likely to adopt a wait-and-see approach, but might use diplomatic and economy pressure if Tsai is seen as straying too far from its unification agenda.

Taiwan was a Japanese colony from 1885 to 1945 and split again from China amid civil war in 1949.

Chu was a late entry in the race after the party ditched its original candidate, Hung Hsiu-chu, whose abrasive style was seen as alienating voters.

China has largely declined to comment on the polls, although its chief official for Taiwan affairs this month warned of potential major challenges in the relationship in the year ahead.

Tsai supporters appeared confident that ties with China would weather a change in government.

"As long as Tsai doesn't provoke the other side, it's OK," said former newspaper distribution agent Lenex Chang, who attended Tsai's rally. "If mainland China democratizes someday, we could consider a tie-up," he added.

Candidates from across the political spectrum sounded a rare note of unity Saturday after a teenage pop star posted a video online apologizing for having waved the Taiwanese flag on a South Korean TV program.

Sixteen-year-old Chou Tzu-yu, who performs under the name Tzuyu, had apparently been compelled to apologize after her South Korean management company suspended her activities in China for fear of offending nationalist sentiments on the mainland.

Ma, Tsai and Chu all condemned what they described as the bullying of a young girl.

Associated Press writer Ralph Jennings contributed to this report.