Gristedes supermarket execs allegedly pocketed more than $3.2 million in bogus “expense” payments as part a tax-evasion scam, an ex-employee charged yesterday.

Former company controller Joseph Grande claims in court papers that he was canned last year after uncovering the alleged 10-year scheme.

His Manhattan federal-court suit seeks more than $100,000 in damages for alleged violations of New York’s “whistleblower” law.

Owner John Catsimatidis said Grande’s allegations were “completely false,” and said the Matawan, NJ, resident was sacked for “poor work performance” that included spending up to a quarter of his time surfing the Web.

Catsimatidis also said Grande, 42, tried to extort $2 million from the company.