Prime Minister Najib Abdul Razak has been challenged to sue businessman Low Taek Jho to disprove the latter's claims that he had close ties with the premier's family.

"This is what Low ( right ) admitted to the international media, he admitted that he is close to Najib's family.

"If this is not true then Najib must sue him immediately," Pandan MP Rafizi Ramli told a public forum in Shah Alam today.

Rafizi said this in response to a remark by Johor Umno Youth deputy chief Khairul Anwar Rahmat that it was unfair to link Low to the prime minister.

The billionaire had in an interview with CNBC said he was an easy target in the 1MDB scandal because of his friendship with Najib's stepson Riza Aziz.

The forum organised by Malay daily Sinar Harian at its headquarters in Shah Alam, was titled "What's behind 1MDB".

Mudslinging upsets audience

However, two speakers Khairul and Rafizi spent a considerable amount of time trading barbs rather than discussing the topic at hand.

At one point, Khairul, who heads Malaysian Volunteer Lawyers Association (SukaGuam), accused Rafizi of deliberately attempting to confuse the public on 1MDB.

"Rafizi has been designed by PKR to memorise names, figures and economic terms that ' mak cik-mak cik kampung ' (village aunties) can't understands... (Terms like) siphon, bailout, the Cayman Islands... (These are all to) confuse the rakyat," Khairul said.

The crowd cheered for both speakers as they took jabs at each other, but some were unhappy with the lack informative content.

"No wonder Sinar doesn't do live telecasts (of forums) anymore, there's more rubbish than knowledge (being presented) today!" exclaimed a man who identified himself as Rosli during the question and answer session.

"Your arguments should not touch on the panel members' personal matters. We (the audience) are not stupid. We follow current affairs [...] we want to hear arguments about 1MDB," said another man who only introduced himself as 'Northerner'.

The forum was moderated by International Islamic University (UIA) political analyst Maszlee Malik and also featured Universiti Teknologi Malaysia (UTM) GeoStrategist Associate Professor Azmi Hassan.