Support is gathering behind Peter Dutton's demand for a parliamentary committee to cut short its public hearings about proposed new cyber laws.

The Home Affairs Minister has written to the committee's chair, Liberal MP Andrew Hastie, stressing the need to speed up its report into encryption access.

Mr Dutton has warned the potential for terrorist attacks over the Christmas holiday period if authorities do not have access to encrypted messaging platforms.

"The situation has become more urgent in light of the recent fatal terrorist attack in Melbourne and the subsequent disruption of alleged planning for a mass casualty attack," Mr Dutton wrote to the committee, in a letter published by The Australian.

"I am gravely concerned that our agencies cannot rule out the possibility that others may also have been inspired by events in Melbourne to plan and execute attacks.

"For these reasons I ask that the committee accelerate its consideration of this vital piece of legislation to enable its passage by the parliament before it rises for the Christmas break."

Attorney-General Christian Porter has questioned why the committee is taking so long to deliberate.

"It seems to me that it can be done far quicker than it is being at present," he told reporters in Perth on Friday.

Government Senate leader Mathias Cormann says it is "very important" for the legislation to be passed as soon as possible.

The committee has scheduled three public hearings on the bill, with the final one set for December 4 - two days before parliament rises for the year.

In releasing a joint statement with deputy chair Anthony Byrne on Thursday, Mr Hastie left the door open for hearings to be cut short.

"The committee will publicly announce any changes to the scheduled hearings as advertised," the statement said.

But Labor leader Bill Shorten says the committee should be given as much time as needed, instead of rushing through with a "botched job".

"We absolutely want to make sure that we can discover what the terrorists are up to, stop them, put them in the jail," he told reporters in Melbourne on Friday.

"But thank goodness this parliamentary committee, made up of Liberal MPs and Labor MPs, has made necessary amendments."

The legislation would require technology companies to hand over encrypted messages to authorities who are investigating crimes.

Australian Federal Police commissioner Andrew Colvin has stressed the need for the laws, arguing there were places law enforcement agencies "can't look, can't see".

"Almost every investigation we have involving terrorism, serious organised crime, child exploitation, involves some levels of encryption," Mr Colvin told ABC radio.