Dr Mahathir Mohamad has used the incident where a movie producer was slapped in front of Prime Minister Najib Abdul Razak to illustrate how freedom of expression has been curbed.

The former premier, who was known to have little tolerance for dissenting views during his tenure, alleged that those who ask Najib questions would end up in trouble.

"This never happened during my time and the prime ministers before me. This only happens during Najib's era ... Those who speak end up in trouble. The newspapers are censored, so is TV3 and other (media)...