People watch a live broadcast of the US presidential election at Seoul Station in central Seoul on Wednesday. (Yonhap)

South Korea's main opposition Democratic Party on Wednesday congratulated former US President Donald Trump on his second term, expressing hopes for a stronger Seoul-Washington alliance.

"We sincerely congratulate him for the win," said Cho Seung-rae, senior spokesman for the DP, expressing optimism that Trump's second term might bring new opportunities for contributing to peace on the Korean Peninsula.

"The DP will work with Trump to ensure that the strong US-South Korea alliance becomes more than just a blood alliance," he added.

According to US media, Republican candidate Donald Trump won more than 270 Electoral College votes in the US presidential election, becoming the first president in more than a century to win a non-consecutive second term.