The government should delay debate on its proposed mandatory data retention legislation at least until a parliamentary committee has investigated its potential impact on journalism, Greens Senator Scott Ludlam has argued.

Debate on the Telecommunications (Interception and Access) Amendment (Data Retention) Bill 2014 is scheduled for tomorrow.

The Parliamentary Joint Committee on Intelligence and Security's inquiry into the impact that police accessing journalists' telecommunications metadata could have on the Australian press will not hold its first hearing until Friday.

"At the bare minimum, wait until the joint committee has had time to examine the issues of how mandatory data retention undermines and compromises investigative journalism," Ludlam today told a press conference.

"The bill should not be debated while issues as serious as whether it compromises investigative journalism are in play and it would be, I think, very strange for the Labor Party to allow this debate to proceed when everybody now agrees that the bill has huge problems that need to be addressed," the Greens' communications spokesperson said.

Opposition leader Bill Shorten has indicated that Labor has concerns over the potential impact of data retention on journalism.

The proposed legislation has been heavily criticised by publishers and broadcasters, as well as the union that represents journalists, the Media, Entertainment and Arts Alliance.

"I am encouraged that it looks as though the Labor Party may not be writing a blank cheque as they did on some of the national security reforms last year, but to me that underlines why the bill should not be debated this week," Ludlam said today.

"I think it would be extraordinary if the government with the consent of the Labor Party brings this bill on and debates it in the House of Representatives when it's got such huge flaws."

Ludlam said there were broader problems with the data retention bill beyond the threat to journalists' ability to protect the identity of their sources.

"Also the question of legal professional privilege which has been raised by the Law Council and by many others over the last couple of weeks, and why ordinary citizens should have to worry about their material being accessed if they're not doing anything wrong and aren't accused of any crime."