The Newcastle United Supporters' Trust (NUST) has accused the club of a "dereliction of duty" towards fans for not providing refunds for postponed matches and continuing to sell season tickets.
A host of Premier League clubs have already committed to refunding season ticket holders on a pro-rata basis for games in the 2019/20 season that will now be played behind closed doors.
Newcastle could soon be under new ownership with a Saudi-led �300 million ($376 million) takeover awaiting the approval of the Premier League.
However, the NUST said that was no excuse for current owner Mike Ashley to withhold refunds.
"We understand the club finds itself in a complex situation in light of the prospective sale of the club by the incumbent owner," the NUST said in a letter to Newcastle's managing director Lee Charnley.
"That does not give you a legitimate right to a dereliction of duty to your supporters."
The letter calls for pro-rata refunds on season tickets, full refunds for single match tickets for home and away fixtures played behind closed doors and a stop to payments for 2020/21 season tickets until that campaign gets underway.
Ashley's 13-year reign as owner of the Magpies has been beset by high-profile clashes with supporters.
The retail tycoon has overseen two relegations from the Premier League amid criticism for a lack of investment on the pitch.
Last week, Newcastle announced a �35 million profit for the 2018/19 season.
Newcastle are yet to offer refunds to fans for matches that will now be played behind closed doors