Grill'd agrees to change its pay rates

Fast food chain Grill'd is changing its pay rates following public backlash after a worker launched legal action claiming she was sacked for asking for fair pay.

Founder Simon Crowe says Grill'd will review its pay agreements, which are currently below minimum wage.

"Our intent is to make sure we very clearly do what's right and enter into modernising our award," he told 3AW radio.

Earlier this week, sacked Grill'd worker Kahlani Pyrah began an online petition and legal action to get her job back.

The 20-year-old had worked at the chain's Camberwell outlet for 12 months when she realised employees were being paid below minimum wage with no overtime or penalty rates.

After Ms Pyrah contacted her union, United Voice, and organised a meeting with Grill'd, the company said it would pay staff what they were owed and pay the award if the current contracts were not terminated.

Ms Pyrah says those conditions weren't met, so she applied to the Fair Work Commission to have the contracts terminated.

She was sacked 11 days later and accused of bullying her managers.

Mr Crowe won't comment on Ms Pyrah's claims now that the matter is before the FWC, but denied the chain was defying the law.

"Legally everyone is in total agreement that we've not done anything inappropriate in this regard," he said.

"We want to make sure, from a fairness perspective, we are above board and we meet the needs of our people."

Ms Pyrah's petition has garnered more than 22,400 signatures since it was launched on Monday.