In a case of mob justice, the group of more than 10 chased after the suspected troublemaker and punched him repeatedly before pushing him into a room which was then locked from the inside.

FMT reporters attempted to enter the room but were told to leave. Sounds of someone being beaten up could be heard through the thin door, which was under heavy guard.

About an hour later, police brought out and escorted two suspects from the VIP room. They appeared weak and unresponsive.

One of them was wearing a red PPBM Youth T-shirt.

When asked about the suspected vigilantes at a press conference later, PPBM Youth chief Syed Saddiq Syed Abdul Rahman said he was unaware of it.

“I really hope you can pass the video to the police. This is not a political matter, this is a criminal matter.

“If there are any members found to have committed vigilante justice, we hope the police will take action against them.

“Because what is wrong is wrong,” he said.

Mahathir, the chairman of Pakatan Harapan, was answering questions at the “Nothing to Hide 2.0” forum this afternoon when out of nowhere, two projectiles with pungent chemical odour were hurled in his direction.

The Dewan Raja Muda Musa hall was then filled with smoke. Punches were said to be have been traded as PPBM members rushed on to the stage to protect the 92-year-old leader.

The incident happened soon after a participant had questioned Mahathir on the Memali incident which saw 14 villagers and four policemen being killed in a confrontation between the police and an Islamic cult in November 1985 in Kedah when Mahathir was prime minister.

“Why, Tun? They were Malaysians. They were Malays, villagers. They were not Jews or Zionists,” the participant was heard saying.

Mahathir kept his cool, replying that four policemen were also killed and that the authorities had used standard procedures in the operation.

*Ivy Chong contributed to this article.