An NFL player and gay rights advocate has spoken out to say that he thinks his vocal support of equal marriage cost him his job.

Chris Kluwe, a former punter for the Minnesota Vikings, on Thursday published an article on Deadspin, in which he said he was “pretty confident” that his sacking came off the back of his equal marriage support.

“I honestly don’t know if my activism was the reason I got fired,” he wrote. “However, I’m pretty confident it was.”

He also described in detail occurrences of homophobia from special teams coordinator Mike Priefer, and confrontations between himself and coaches or press officers over his decision to speak out publicly.

“As we sat down in our chairs,” Kluwe wrote of one meeting, “Mike Priefer, in one of the meanest voices I can ever recall hearing, said: ‘We should round up all the gays, send them to an island, and then nuke it until it glows.'”

Fighting in the state of Minnesota against a now rejected constitutional amendment to ban equal marriage was one of Kluwe’s acheivments. The amendment was rejected in November 2012, and Kluwe was cut by his team in May 2013.

At the time he said he was very careful about the wording of his response when asked whether he thought gay rights advocacy had an impact on his job, but now he has said that he was told to “be quiet”.

Neither the NFL nor Priefer have commented on the allegations, although the Vikings released a statement on Thursday denying that Kluwe was sacked for his gay rights avocacy.

“We do not tolerate discrimination at any level,” the statement read. “Any notion that Chris was released from our football team due to his stance on marriage equality is entirely inaccurate and inconsistent with team policy. Chris was released strictly based on his football performance.”

The club said it had investigated the allegations.

Some have questioned this, however; noting his strong record as a punter at the Vikings. Kluwe mentioned his performance in the blog post.

“Some will ask if the NFL has a problem with institutionalized homophobia,” he continued. “I don’t think it does. I think there are homophobic people in the NFL, in all positions, but that’s true for society as well, and those people eventually get replaced.

“All we can do is try to expose their behavior when we see it and call them to account for their actions.”

Kluwe made the headlines in September 2012 when he defended Brendon Ayanbadejo, formerly of the Baltimore Ravens, against a call from Delegate Emmett C Burns Jr, to reprimand Ayanbadejo, who recorded a video for a gay rights advocacy group In October 2011.

In a response to Burns, he wrote: “I can assure you that gay people getting married will have zero effect on your life. They won’t come into your house and steal your children. They won’t magically turn you into a lustful cockmonster.”

This revelation echoes that of former Baltimore Ravens linebacker, and equal marriage advocate, Brendon Ayanbadejo, who retracted a statement saying that he thought he was cut for his equal marriage advocacy.