Australia's workplace laws need a "rethink" according to Coles managing director John Durkan, who hit out at the nation's industrial relations system, claiming it disadvantaged customers and discouraged innovation and productivity.

The supermarket boss called for the simplification of industrial relations after revealing Coles' latest Store Team Agreement was mired in argument before the Fair Work Commission.

Coles boss John Durkan says Australian grocery prices are still too high. Credit:Robert Prezioso

"Coles is currently defending a challenge to the approval of our latest Store Team Agreement, more than a year after our team members voted overwhelmingly in support of it," Mr Durkan said at an American Chamber of Commerce in Australia event.

"Under the current workplace relations laws, one team member, a weekend casual represented by a union official from an unrelated union, has been able to hold the fate of 75,000 people's working conditions hostage over months of argument before the Fair Work Commission."