Labor groups and investors have filed a shareholder proposal asking Apple Inc to review how it treats workers' rights, looking to build on recent momentum to unionize workers at the iPhone maker's retail stores.

The proposal filed by a group including SOC Investment Group, a consultant to union pension funds, and an arm of the Service Employees International Union, accuses Apple of an "apparent misalignment" between its public commitments to things like freedom of association and accusations it has tried to unfairly deter union organizing.

"If a corporation's values and their behavior diverge, that's a problem," said Dieter Waizenegger, SOC executive director.

An Apple representative declined to comment.

The company is scheduled to hold an event Wednesday where it is expected to introduce new iPhones.

Other filers of the proposal include New York City Comptroller Brad Lander who oversees pension funds, Trillium Asset Management and Parnassus Investments.

Apple is among American companies that face unionization efforts along with Starbucks Corp and Amazon Inc.

Workers at a Maryland Apple store voted to unionize in June and efforts are under way in other states.

Shareholder proposals for Apple's 2023 annual meeting are due Sept 8.

At this year's meeting on March 4 two resolutions won a majority of votes cast including one asking Apple to conduct a civil rights audit whose filers included some of the same union-affiliated investors.

The other successful resolution asked Apple for a review of its use of non-disclosure clauses and other agreements that limit worker speech.

Filer Kristin Hull, chief executive officer of Nia Impact Capital, said the firm has not been able to meet with Apple's board since. Nia has submitted a new resolution for 2023 asking board members be more accessible.