Prime Minister Malcolm Turnbull has defended his use of a non-government email service since taking the nation's top job.

Well known for his love of technology, the former communications minister said earlier this year he used secret messaging app Wickr because it provided superior security.

Wickr claims it allows users to send encrypted messages to other users of the app, leaving no traceable metadata, with the messages self-destructing after being read.

Mr Turnbull's use of services outside of Federal Parliament's secure servers has continued since he moved into the Prime Minister's office, but a spokesman stressed the server is located in Australia.

"To suggest that every government, every piece of government or communication by a politician that relates to his or her office can only be transmitted on a government email account or to a government email account would mean you could never write a letter to your constituent, you could never use SMS," Mr Turnbull said.

"Classified information can't be transmitted to, or transmitted from, anything other than a government system that is certified as appropriate for it.

"The answer is I can't do it, and I wouldn't do it, and I protect classified information very carefully."

Mr Turnbull said many MPs use similar services.

"Firstly, you shouldn't assume that government email services are more secure than private ones ... but nonetheless we do have rules relating to them," he said.

"Secondly, I can tell you that text messaging, which is widely used, is the least form of communication — it's unencrypted in transit and unencrypted at rest.

"Over-the-top applications [such as Wickr] ... there are a number of over-the-top applications that offer a much higher degree of security."

Shorten calls for Turnbull to explain actions

Mr Turnbull's use of non-government email services come as US Democratic Party presidential candidate Hillary Clinton continues to defend her use of a private email account and home server in lieu of the official government email system while she was secretary of state from 2009 to 2013.

She denied using a private email account to send or receive classified information during her time as the nation's top diplomat.

In September, Mrs Clinton apologised.

"That was a mistake. I'm sorry about that. I take responsibility," she said in an interview.

"As I look back at it now, even though it was allowed, I should have used two accounts, one for personal emails, one for work-related emails."

Earlier, Opposition Leader Bill Shorten said Mr Turnbull needed to explain his actions.

"Malcolm Turnbull should just come and explain what's been used, has there been any classified information sent," he said.

"It's important for the Prime Minister to realise he's that same as everyone else, the same rules apply to all of us.

"The real issue here is you don't send classified material on your personal emails.

"Malcolm Turnbull's now in charge of the nation, there are rules for this, he can clear this up just tell us what's happened when and put the facts on the table."

Turnbull should have expected criticism: expert

Australian National University cyber-security expert Tom Worthington said Mr Turnbull should have foreseen he would be criticised for the use of a non-government server.

"It's something perhaps the Prime Minister's office should have anticipated and perhaps explained that the Prime Minister's using certain services," Mr Worthington said.

"It's a bit different, my understanding is Hillary Clinton was using, in effect, her own private email server and the intention there was effectively to circumvent the system.

"If you're using a commercial email service that's being carried through the telecommunications network, it will be covered by all of the same rules that apply to a Government-based service."

Mr Worthington said it was an example of a Prime Minister's office adjusting to new technology.

"This is how we should be running the Government today," Mr Worthington said.

"Barack Obama famously uses his device for doing this. I would hope that other ministers and members of parliament follow this example, but that they just check to make sure they're using the secure facilities that are appropriate for what they're doing."