Police will question PKR vice-president Rafizi Ramli over his 'bomb' comment made at a ceramah on June 9.

Perak police chief Datuk Seri Abd. Rahim Hanafi said police have opened investigation papers under Section 506 of the Penal Code for criminal intimidation.

"Rafizi on June 9 in a ceramah said he wants to bomb the prime minister. We have opened investigation papers. I am not sure how many people will be called in for questioning. Police are still investigating," he said when met during the early voting process at Kuala Kangsar today.

A total of 312 early voters comprising policemen are eligible to cast their ballots in the Kuala Kangsar by-election today.

Early voting is held at Dewan Tun Salleh Ismael, Kompleks Perumahan Polis at Kuala Kangsar district police headquarters and Manong police station meeting room.

There are 32,949 registered voters in Kuala Kangsar.

On Monday, local residents lodged four police reports following Rafizi's comment to bomb Prime Minister Datuk Seri Najib Razak if Parti Amanah Negara candidate wins the by-election.

READ: Early voting begins in Kuala Kangsar by-election

Ab Rahim also advised political parties contesting there not to engage in provocative actions

The Kuala Kangsar by-election was called following the death of its incumbent Datuk Wan Mohammad Khair-il Anuar Wan Ahmad in a helicopter crash in Sebuyau, Sarawak on May 5.

The by-election is a four-cornered fight involving Barisan Nasional (BN), PAS, Amanah and Independent.

The by-election will be held on June 18.