One of the world’s biggest news outlets, Thomson Reuters, has joined a number of companies in protesting Minnesota’s proposed gay marriage ban.

In a statement, the firm said the proposed constitutional amendment would not “be good for Thomson Reuters or the business community in the state”.

Minnesota already bans gay marriage but anti-gay campaigners say a constitutional amendment is needed to protect the ban. Voters will decide the issue in November.

Other large companies, including General Mills and St Jude Medical, have already come out against the proposal.

An email to Thomson Reuters employees on Friday said: “We believe the Minnesota Marriage Amendment, if passed, would limit our ability to recruit and retain top talent.

“For this reason, we do not believe that the amendment would be good for Thomson Reuters or the business community in the state.”

It added: “As we’ve heard from employees, recruiters and customers, one thing has been very clear: we’re a better place when we have a rich variety of perspectives, talents, backgrounds, lifestyles and experiences in our workplace, and within the broader community from which we recruit.

“We believe that building a culture that thrives on diversity and inclusion and provides equal opportunities to everyone is a critical factor in our ability to serve our customers and be successful.”

Media commentators have noted that companies around the US are becoming bolder in their support for gay rights and marriage equality. Recently, 50 major companies, including Nike, Xerox and Time Warner, signed a court briefing against the Defense of Marriage Act (DOMA), which denies federal benefits to same-sex couples.