The Fair Work Ombudsman will investigate fast food franchise, McDonald’s, for allegedly underpaying workers after the industrial relations commissioner Donna McKenna rejected an agreement aiming to protect employees nationwide.

McDonald’s Australia CEO, Catriona Noble said she is disappointed with McKenna’s decision to decline the approval of the McDonald’s and the Shop Distributive and Allied Employees Association (SDA) National Enterprise Agreement, which sought to secure the terms and conditions of the franchise’s employees.

The Agreement was reached in conjunction with the SDA, with both parties satisfied that employees would gain from increased benefits and greater flexibility under the new agreement, she said.

According to a statement issued by McDonald’s, more than 35,000 employees voted and of them a total of 31,970 voted yes for the Agreement.

The Agreement includes a $10 per week upfront wage increase for full time adult employees in most states/territories, a guarantee of increases from Fair Work Australia’s national pay decisions and casual loading increases from 20 per cent to 22 per cent over the life of the Agreement.

The Fair Work Ombudsman is investigating whether McDonald’s employees have been underpaid, following a referral from Fair Work Australia, said Fair Work Ombudsman group manager, field operations, Bill Loizides. Any workers concerned that they have been underpaid – any parents with concerns their children have been underpaid – can contact the Fair Work Infoline on 13 13 94 for advice and assistance.

The matter was referred to the Fair Work Ombudsman after McKenna explained that there is evidence which suggests certain McDonald’s employees have been underpaid.

McDonald’s is currently exploring grounds for appeal.