Sutton United have denied accusations they have censored a group of supporters from a club forum after they voiced their opposition to the Sun’s sponsorship of the National League side’s FA Cup tie against Arsenal on Monday night.

Earlier this week, Sutton announced a deal with the Sun that is understood to be worth a five-figure payment that will see Sun Bets replace their usual sponsor, Green Go Waste, for the historic match against Arsène Wenger’s side at Gander Green Lane.

It was greeted with scepticism by some supporters after the agreement came within days of Liverpool’s decision to ban the newspaper from Anfield and their Melwood training ground over its notorious coverage of the Hillsborough disaster, in which 96 Liverpool supporters were unlawfully killed.

According to one supporter who wished to remain anonymous, “there was an immediate outpouring of concern on the SUFC forum” – an independent site run by fans that is also accessible via the club’s website.

“For many of us, this goes against our whole ethos of being a volunteer-run community club,” the supporter added. “Many of us have gone on record as expressing our serious concern at the choice of sponsor, especially in light of the fact that post-Hillsborough, we regard them as a toxic brand that no football club, especially not a non-league football club which is justifiably proud of its independence, should do business with. We would have much rather they had come to their own community for an extra injection of cash rather than go with the Sun, which many of us see as absolutely toxic.”

But the supporter has also alleged that the club, rather than accept the criticism, has taken active steps to gag their opposition. A thread with the title “Sh*t sponsor” which was posted within hours of the deal being announced was deleted. When questioned why this was the case, the forum’s chief administrator posted a message explaining the thread at been deleted “at the request of the club”.

The supporter, who was one of several hundred Sutton fans to buy shares in the club last summer after a request form the board, also claims he has since been banned from the forum after posting his opinion. The ban is not set to be lifted until after the cup tie against Arsenal.

Another thread entitled “Shirt Sponsor” remains online, with several fans taking the opportunity to vent their anger at the decision – including one of Muslim origin who wrote: “I know a few people who are walking away and I’m done with the club now too. It’s unfortunate but I don’t feel valued by this club at all and I can’t relate with a club that promotes the Sun, especially as a Muslim.”

Another thread entitled “Unacceptable behaviour from a Sutton ‘supporter’” details an allegation that another forum member received an anonymous telephone call warning them to “keep their mouth shut” and to “support Sutton”.

“Although I am keeping that member’s detail anonymous, they were someone who showed discontent on here about some of the matters in the last few days,” wrote another of the site’s administrators, Andy K. “On this board we have an obligation to respect our members and I’m sure many of you would agree that this is taking a disagreement to an unacceptable level. The club have been informed accordingly.”

The Guardian contacted Sutton for a response and they insisted they have not asked for anything to be removed. “As the forum is independent of the club we have no power to ban anyone from using it,” read a club statement.

The forum’s chief administrator, Nick, later claimed responsibility for removing the original thread only because the deal with the Sun had yet to be made public. “It was my decision to remove the thread and not the club’s,” he said. “Only one person has been banned and that was for continually personally attacking me. I’ve let many people go on there and criticise the club, even though it breaks my heart because we are a fantastic club. I’ve had this forum for 10 years and in that time, nobody else has been banned.”

A Sun spokesperson added: “The whole basis of this story has been denied by the club and the quotes are taken from anonymous message boards. The Sun’s football coverage remains hugely trusted and enjoyed by millions, as evidenced by the newspaper’s continuing success as the most-bought in Britain.”

However, the supporter who highlighted the story believes he has been made a scapegoat.

“I am horrified by what is happening to my club,” he said. “Just because I and other fans objected to being sponsored by the Sun, we are being irresponsibly portrayed by some as being against the club we love, support, and financially back.

“The people who feel strongly about this have not been treated well by the club, that is for sure. The sad thing is this club has never been like this until the Sun sponsorship came along – we’ve always been friendly and respectful of each other. This is the first time things have gone sour.”