Australian Prime Minister Malcolm Turnbull has said social media companies are too tolerant of extremist material, and called on those companies to help bust the encryption used in user communications.

"We need these global social media messaging companies to assist in providing access to encrypted communications, which are used by billions of people," Turnbull said on Monday.

"The security services need to get access to them."

The prime minister said the Five Eyes countries -- the US, the UK, Australia, Canada, and New Zealand -- are working with social media companies such as Facebook and Twitter to get extremist material taken down.

Saying nations and their agencies need to be smarter, more agile, and more collaborative than those "who are seeking to do us harm", Turnbull agreed with the thoughts espoused by British Prime Minister Teresa May over the weekend.

May called for the introduction of rules to "deprive the extremists of their safe spaces online", and also hit out at technology firms for not doing enough.

"We cannot allow this ideology the safe space it needs to breed. Yet, that is precisely what the internet and the big companies that provide internet-based services provide," said May.

May's comments followed the UK suffering its third terrorist attack in four months.

Last week, Australian Federal Police (AFP) Commissioner Andrew Colvin said tackling the online world is a "'genuinely wicked problem" for police forces.

"Technology presents challenges to governments like almost never before," Colvin said. "It is a realm that we cannot simply legislate or regulate to control -- we must work with the industry who have their hands on the levers, and invariably, they are in the private sector."

Colvin called for the use of traditional and non-traditional policing capabilities to ensure criminals cannot hide behind encryption to avoid the law.

"Prolific growth in the use of encryption technology is an everyday reality for investigators, and we cannot afford for this to remain an obstacle."