Wal-Mart, the world’s largest retailer, fired back at a prominent proxy advisory firm that critiqued the company’s executive pay plan and how it’s handled an overseas bribery probe.

Institutional Shareholder Services earlier this week urged shareholders to vote against Wal-Mart’s executive compensation package and asked them to back a resolution for the appointment of an independent chairman.

It also recommended shareholders vote against the re-election of board members Robson Walton, the company’s chairman, and Mike Duke, recently Wal-Mart’s CEO.

The ISS cited the failure of the board to provide more information to shareholders about specific findings of an investigation into bribery outside of the United States.

Those issues go to a vote at the company’s shareholder meeting on June 6. The meeting will be held in Fayetteville, Arkansas, about 30 miles from the company’s headquarters in Bentonville.

In a filing with the Securities and Exchange Commission on Thursday, Wal-Mart said that the ISS analysis “misconstrues the nature and operation of Wal-Mart’s executive compensation programme.”

Wal-Mart said the ISS analysis is based on information provided by CtW Investment Group, a union-backed organisation, that has a long history of opposition to Wal-Mart.

ISS cited changes that it believes have diminished the consistency of performance goals set for company executives.

Wal-Mart said its pay structure emphasises performance and is “intended to closely align the interests of our named executive officers with the interests of our shareholders.”