Prime Minister Lee Hsien Loong took the stand in the High Court yesterday at the start of a four-day hearing in his defamation suit against blogger Leong Sze Hian.

PM Lee is suing Mr Leong over a post the blogger and financial adviser shared on his Facebook page in 2018, which contained a link to an article by a Malaysian news site.

The article alleged that former Malaysian prime minister Najib Razak had signed "secret deals" with PM Lee in exchange for help from Singapore banks in laundering money from scandal-ridden state fund 1Malaysia Development Berhad.

PM Lee's lawyer, Senior Counsel Davinder Singh, said in his opening statement that Mr Leong continued to insist the article falsely linking PM Lee to the 1MDB scandal in Malaysia was true, even after he had removed the Facebook post that linked to it.

At the hearing, Mr Leong's lawyer Lim Tean contended that PM Lee had no justification to take legal action against his client, and argued he had picked on Mr Leong because he is a staunch government critic.

PM Lee said he had a responsibility to vindicate his reputation.

Today, Associate Professor Tuan Quang Phan of Hong Kong University Business School, a social media academic, will give evidence via video link as an expert witness for PM Lee.