New York City Mayor Michael Bloomberg has pledged another $500,000 to support pro-gay marriage campaigns in Maine, Washington state and Minnesota.

“Marriage equality is the next big step in America's long march of freedom,” Bloomberg said in a statement announcing the contributions. “I do not believe that government has any business telling one class of couples that they cannot marry.”

The contributions are intended to spur matching donations.

Bloomberg is giving $250,000 to the campaign supporting Referendum 74, which would uphold a gay marriage law approved by Washington lawmakers.

The campaigns to defeat a constitutional amendment defining marriage as a heterosexual union in Minnesota and legalize gay nuptials in Maine will each receive $125,000.

According to Minnesotans United for All Families, Bloomberg's gift has already been matched by a dozen Minnesota businesspeople.

“Business leaders across the state – and those around the nation, like Mayor Bloomberg – have made it clear that this amendment is bad for business,” said Richard Carlbom, campaign manager for Minnesotans United for All Families.

Bloomberg, considered a key ally in legalizing such unions in New York last year, earlier this month gave $250,000 to the campaign working to uphold a similar law in Maryland.