The opposition leader foreshadowed the pledge while detailing Labor's women's policy platform in Melbourne on Friday.

"We'll be announcing new plans to cut the cost of long day child care and we will lead a new national push for pay equity, starting with early childhood educators," Mr Shorten said.

Labor also plans to make big businesses publicly report their gender pay gaps by banning secrecy clauses.

"If your company isn't trying to close the gender pay gap, you won't be able to cover it up any longer," Mr Shorten said.

The pay equity push would also extend to the public service under Labor.

Departments and agencies would be made to audit their pay gaps and find out the causes. Pay equity would also be restored as a principle of enterprise bargaining.

"If you're not paying men and women equally, from now on, you're going have to explain why not," Mr Shorten said.

"And what's more, you'll need to show you've got a plan to fix it."

Companies seeking government contracts would also need to report on their gender pay gaps and plans to achieve parity between men and women.

"Companies that do the wrong thing shouldn't get a competitive advantage or a single taxpayer dollar," Mr Shorten said.

Australian Associated Press