ST. PAUL, Minn. — General Mills - the owner of Wheaties, Betty Crocker, Green Giant and other iconic American brands - said Thursday it opposes a proposed Minnesota constitutional amendment to ban gay marriage, the largest company in the state to come out against the measure so far.

"We do not believe the proposed constitutional amendment is in the best interests of our employees or our state economy — and as a Minnesota-based company we oppose it," Ken Charles, vice president of global diversity and inclusion for General Mills, wrote in a letter to employees and the public, the Star Tribune reported. "We value diversity. We value inclusion. We always have and we always will."

A company spokeswoman did not immediately return a call from The Associated Press requesting a copy of the letter.

"This will go down as one of the dumbest corporate PR stunts of all time," warned Brian Brown, president of the National Organization for Marriage, a group pushing for the amendment.

NOM has spearheaded campaigns against other pro-gay marriage corporations, including Starbucks.

Minnesota already bans gay marriage by statute, but gay marriage opponents have said putting the ban in the state constitution would make it harder for courts to undo it. Voters will decide the issue in November.

Minnesota for Marriage, another group pushing for the amendment's passage, accused General Mills of "pandering to a small but powerful interest group."

"By taking this position, General Mills is saying to Minnesotans and people all around the globe that marriage doesn't matter to them," Chairman John Helmberger said in a statement.

Executives from St. Jude Medical, RBC Wealth Management and Carlson Companies also have publicly opposed the proposal.

Businesses have found it can be risky to take sides on polarizing social issues. Target Corp. suffered a backlash two years ago after making a political donation to a Republican candidate for governor who opposed gay marriage. The company was criticized again earlier this month for selling gay pride T-shirts to raise money for a group working to defeat the gay marriage ban.

The Associated Press contributed to this report.

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