Talk about a Mexican standoff.

Walmart is refusing to budge an inch after critics bashed the retail giant for overpaying its executives while they mishandled a probe into charges that it systematically bribed officials in Mexico.

Proxy adviser Institutional Shareholder Services “misconstrues” Walmart’s executive compensation policies, the discounter said in a regulatory filing Thursday.

ISS based its analysis on information from CtW Investment Group, a union-backed group that has long opposed Walmart, the filing charged.

The Bentonville, Ark., retail giant said its pay practices are “intended to closely align the interests of our named executive officers with the interests of our shareholders.”

Earlier this week, ISS, which advises mutual funds and other big investors on how to vote on corporate ballots, called for Walmart to oust directors — including longtime Chairman Rob Walton — amid rising controversy.

ISS gripes that Walmart hasn’t disclosed which of its executives and directors — including Walton, the eldest son of the retailer’s legendary founder Sam Walton — might be culpable in the bribery investigation.

The proxy adviser likewise blasted Walmart for adjusting the performance targets used to calculate executive pay, with the result that execs, including current CEO Doug McMillon and former CEO Mike Duke, are reaping millions despite mediocre sales and profits.

Because Walmart’s performance last year was lackluster, Duke, who stepped down as CEO earlier this year, saw his bonus slashed by $1.5 million, while McMillon got his clipped by $519,000, the company said in the filing.

CtW Investment Group shot back Thursday that cash incentive payouts to Duke and McMillon didn’t fall as drastically short of their targets as the company’s performance did.

Meanwhile, Walmart said disclosing “specific findings” related to possible violations of the Foreign Corrupt Practices Act, which can include bribery, could interfere with the ongoing investigations.

The pay issues will be put to a vote at Walmart’s annual shareholder meeting June 2.