Shares in fast-food chain Domino's Pizza Enterprises have slid on revelations the Fair Work Ombudsman is investigating stores for alleged underpayment of staff.

A spokesman for the ombudsman said: "In recent months FWO has conducted a number of site visits at Domino's outlets across the country. These visits are continuing and as such it would be inappropriate to make further comment at this stage."

It's unclear how many complaints have been made about Domino's stores.

Domino's said it had "no tolerance for any franchisee failing to meet their obligations to their employees and is leading our industry in this effort".