Former prime minister Tun Dr Mahathir Mohamad's statement to do things 'outside the box' to topple Prime Minister Datuk Seri Najib Tun Razak can be considered seditious, says Home Deputy Minister Datuk Nur Jazlan Mohamed.

He said Dr Mahathir made the statement on Sunday, during the closed-door gathering with opposition leaders in Shah Alam, Selangor.

"He (Dr Mahathir) said it publicly, that he is going to do things 'outside the box', going beyond the constitution.

"Is that action not seditious? Or even treacherous?," he asked reporters at the Parliament lobby here today.

Thus, Nur Jazlan said the Royal Malaysian Police (PDRM) would conduct an investigation into the various comments made by Dr Mahathir in his persistent attempts to topple the prime minister.

"Dr Mahathir just wants to get publicity and political mileage. The police are investigating. The more he talks, the more mistakes he will make and there will be more material for the police to investigate.

"If investigations show that he has violated the law, then we will take action," he said.

On Pandan MP, Rafizi Ramli's alleged exposure of documents related to 1Malaysia Development Berhad (1MDB), classified as official government secret under the Official Secrets Act 1972 (OSA), Nur Jazlan said the police had opened an investigation paper on the matter.

He said the government was currently reviewing and amending the OSA to streamline existing provisions in the act, given the cursory attitude of some parties on the enforcement of the OSA.