The police have once again grilled Dr Mahathir Mohamad, this time for his statement likening Prime Minister Najib Abdul Razak to Ugandan dictator Idi Amin.

Amin, during his tenure as president from 1971 to 1979, was known for human rights abuses, corruption and killings.

It is believed that the case against Mahathir has been classified under the Sedition Act.

Mahathir had made the comparison in his speeches in the run-up to the Kuala Kangsar and Sungai Besar by-elections, calling Najib the "Idi Amin of Malaysia".

A team from the Bukit Aman police headquarters recorded the former prime minister's statement at his office at the Perdana Leadership Foundation in Putrajaya this morning.

Speaking to reporters later, Mahathir said he would not retract his statements.

"I won't retract. I didn't say that he (Najib) killed people, but I did say that he is a bad president (prime minister)," he added.

Mahathir also told reporters that the questioning session was brief as he had declined to answer most of the questions.

He said he only admitted to making the comparison between Najib and Idi Amin, and details such as the time and place where he made the remarks.

"As for the specific accusations against me, I will only answer them in a court of law," he added.

Mahathir said the police would return after the Hari Raya Aidilfitri celebrations next week to question him again on one of his blog postings.

In his speech following BN’s thumping victories in the June 18 by-elections, Najib took a swipe at Mahathir, saying the results showed that the ‘Idi Amin of Malaysia’ turned out to be popular.