New York Mayor Michael Bloomberg has donated $250,000 (£155,430) to the campaign that is fighting to keep equal marriage in the US state of Maryland.

A bill to legalise same-sex marriage in Maryland was passed by the Maryland General Assembly in February 2012 and signed into law on 1 March 2012, by Democratic Governor Martin O’Malley.

However, opponents of marriage equality have successfully gathered enough signatures to force a referendum on the decision – which is taking place on 6 November.

“As a business leader and mayor of New York City, I do not believe that government has any business telling one class of couples that they cannot marry,” Mr Bloomberg said in an email, reported by the Washington Post.

Mr Bloomberg also mentioned his Maryland ties and said that the state’s Governor Martin O’Malley had asked for his support on the issue.

“Maryland will always hold a special place in my heart,” Bloomberg said. “I went to college at Johns Hopkins in Baltimore, and have remained active in the Hopkins community. So when Governor O’Malley asked me to support Question 6, I didn’t hesitate,” Mr Bloomberg said.

He also referred to New York’s historic decision to introduce marriage equality last year in the email.

Last month, Maryland Marriage Equality held a major fundraiser in New York City. Comedian Sandra Bernhard, Susan Sarandon and former president George W Bush’s daughter Barbara attended the event along with gay former Republican National Committee chairman Ken Mehlman.