The police have summoned DAP lawmaker Tony Pua over a video he posted on Facebook, which allegedly contained defamatory remarks against Prime Minister Najib Abdul Razak.

The Petaling Jaya Utara MP told Malaysiakini that he has been asked to be present at the Bukit Aman police headquarters in Kuala Lumpur tomorrow morning.

“This is related to the video which Najib has sued me (for)...

“Somebody lodged a police report on it. I don't know what the police intend to ask me, but I will give them my full cooperation,” he added.

Pua also refused to speculate who was behind the police report.

When asked whether he expected to be arrested tomorrow, Pua replied, "Don't think so".

Last Friday, Najib filed a defamation suit against Pua over the video which was related to the Syariah Court (Criminal Jurisdiction) Act 1965 (Act 355) amendments.

In a letter of demand sent earlier, the prime minister's lawyer Hafarizam Harun said the video had implied that his client committed theft and abused his power.

“Contrary to your defamatory statements above, our client is not a tyrannical and oppressive kleptocrat, nor does he shun criticisms, neither he is a leader involved in corrupt practices nor a leader who steals the people's monies.

"Accordingly, your entirely baseless and false allegations are intended to disparage our client's high political standing, immense goodwill both local and international and unblemished record of performance.

"In doing so, you were acting with malice prepense," he stated.

This is Najib's second defamation suit against Pua. In 2015, he sued the DAP MP over comments linking the prime minister to the 1MDB scandal.

Pua has also filed a suit against Najib this year for alleged "misfeasance in public office".