The police have described as appropriate, the arrest of two Australian journalists who broke through a security cordon and tried to aggressively approach Prime Minister Datuk Seri Najib Tun Razak in Kuching last Saturday.

Deputy Inspector-General of Police Datuk Seri Noor Rashid Ibrahim said the action was necessary to protect and ensure the safety of leaders, besides maintaining public order.

"In today's world which is exposed to possible threats by the Daesh (Islamic State) militant group, security of leaders is a priority, hence it (security) must be tightened," he told reporters after witnessing the handing-over of duties to the new Kuala Lumpur police chief here Monday.

Former federal CID (investigations/legal) deputy director Datuk Amar Singh Ishar Singh, 58, was appointed city police chief to replace Datuk Tajuddin Md Isa, who was appointed Bukit Aman Commercial Crime Investigation Department deputy director.

In the 8.35pm incident, the police nabbed the Australians for aggressively trying to approach Najib, who was on an official visit to the Darul Ehsan Mosque at Kampung Haji Baki in Kuching.

They were taken to the Padawan district police headquarters for questioning before being released on Sunday on police bail after their statements were recorded.

The Australians, aged 51 and 39, claimed to be reporters from the Australian Broadcasting Corporation based in Sydney.

Denying the duo were linked to the Islamic State group, Noor Rashid said they appeared to be investigative journalists.

"However, their action was a bit overwhelming, hence we had to detain and question them," he added.