Police have initiated investigation on former prime minister Tun Dr Mahathir Mohamad concerning his recent statement in his blog which was alleged to be slanderous.

Inspector-General of Police Tan Sri Khalid Abu Bakar said the investigation was initiated as soon as reports were received from several quarters who wanted immediate action to be taken on the matter.

"The police report was received a day or two ago...every action must follow legal procedures and comply with all the legal processes. We cannot be emotional in all matters.

"(Later) we will discuss with the Attorney-General's Chambers, when (it's proven) there is a case for action to be taken, then we will act," he told reporters after the Handing-Over of Duty of the Penang Chief Police Officer from Datuk Seri Abdul Rahim Hanafi to Datuk Abdul Ghafar Rajab.

In his blog on Feb 5, Dr Mahathir had stated that Attorney-General Tan Sri Mohamed Apandi Ali had no credibility and claimed that the latter would not take action against Prime Minister Datuk Seri Najib Tun Razak in the SRC International case and the RM2.6 billion fund as he was purportedly indebted to Najib for the appointment.

In another development, Khalid said police would cooperate fully with the Immigration Department concerning the entry of 1.5 million Bangladeshi workers.

Asked whether a tighter screening process would be carried out on these workers, he said: "Yes, we will take the necessary steps in ensuring that they do not pose any threat to us."

Abdul Ghafar was previously the Director of the Department of Integrity and Standard Compliance (JIPS) Bukit Aman.

Meanwhile, Abdul Rahim who had served in Penang since 2012, moves to Perak as its Chief Police Officer.