This week's election in the Central American nation has been closely watched in Taipei because Honduras is one of just 15 countries that still diplomatically recognise Taiwan over Beijing.

Castro, the leftist wife of ousted former president Manuel Zelaya, has said she will "immediately open diplomatic and commercial relations with mainland China" if she wins.

On Wednesday, Taiwan's President Tsai Ing-wen said she hoped Castro would instead "deepen traditional bonds" between Taiwan and Honduras.

"On behalf of our government and people, President Tsai extends her sincere congratulations to Ms. Castro for being elected as the new president of Honduras," her office said in a statement.

Tsai hopes that under Castro's leadership "official relations between the two countries continue to be friendly and deepen".

In a separate message on Twitter, Tsai said she looks forward to working together for "the deepening of the traditional bond that has always united Taiwan and Honduras".

China claims Taiwan as part of its territory awaiting reunification, by force if needed.

It has spent decades successfully encouraging Taiwan's diplomatic allies to switch sides, a campaign it ramped up after Tsai's 2016 election.

Since then China has poached seven of Taiwan's diplomatic allies, including three in Latin America -- Panama, El Salvador and the Dominican Republic.

Before the election, Taiwan warned Honduras against "flashy and false" promises by China, after Castro of the main opposition Liberty and Refoundation Party said she planned to switch sides.

Castro looks set to be the first woman to rule a Central American nation after her rival from the ruling rightwing National Party conceded defeat.

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