Prime Minister Najib Abdul Razak has received flak for not speaking up against the assault that took place in his presence during a Transformasi Nasional (TN50) dialogue at Seri Perdana last night.

"This outrageous and shameful attack took place right in front of the prime minister.

"At the time of the assault, (filmmaker) David Teo was holding a microphone and merely trying to ask a question to the PM from the floor.

"It is shocking and unacceptable that the prime minister of Malaysia, having witnessed at close quarters this act of criminal violence, said nothing immediate to condemn or disapprove of the assault," said Padang Serai MP N Surendran in a statement.

Teo was slapped by comedian Sulaiman Yassin while asking the prime minister a question on stage.

Najib was reported to have kept calm during the incident, and later asked the duo to shake hands in front of the participants of the dialogue.

Surendran however said the prime minister's actions give the impression that such behaviour is condoned.

"When a criminal act has taken place, neither the PM nor anyone else has any business trying to settle the matter between them," said the PKR lawmaker.

"The police must investigate and the law must take its course. Failure to take action or trying to 'settle' between the parties, is tantamount to condoning criminal violence and public hooliganism," he said.

No to 'mob justice'

The assailant, also known as Mat Over, told Malay daily Harian Metro today he slapped Teo to teach him "some manners".

"I don't think it was extreme to teach him some adab (manners), especially when in front of a leader, who is also the host of the event," Sulaiman was quoted saying.

While Teo does not plan to take legal action against his attacker, Harian Metro reported a NGO called 'Pertubuhan Pembela Nasib Melayu Malaysia' plans to lodge a police report against the film director.

Surendran meanwhile said regardless of Teo's alleged behaviour being claimed to be "rude", no one has the right to physically assault him.

"Mob justice is illegal in Malaysia," he said.

"The attacker has, in full view of TV cameras, committed criminal offences for which he can be charged under sections 351 and 321 of the Penal Code," he said, referring to 'assault' and 'voluntarily causing hurt'.

"The prime minister must now explain to the public his failure to immediately condemn the act, even though he had a microphone and could have spoken out."

Surendran said the inspector-general of police should "direct an immediate investigation" since the incident and the perpetrator are clearly seen on video recordings.

"At all costs, the rule of law must be upheld," he said.