Chelsea fans are "upset and confused" that a website part-owned by Chelsea chairman Todd Boehly is offering tickets for the club's FA Cup semi-final with Leeds at Wembley Stadium at hugely inflated values.

Vivid Seats, an American resale platform in which Boehly is a minority shareholder, has ticket listings for the semi-final clash with Leeds on 26 April at Wembley priced between $200 (£148) and $2,308 (£1,705).

The prices far exceed face value - between £30 and £150 - and the listings have been online since before tickets were made available to Chelsea season ticket holders via the club on Friday morning.

Over 100 ticket listings were displayed on the website, in all four stands of the stadium including areas designated to both Chelsea and Leeds fans, and in hospitality lounges.

Prices are determined by sellers on Vivid Seats, which earns money from each sale.

The ticket listings are not visible for UK customers, meaning the practice does not fall foul of the law, but BBC Sport was easily able to access listings using a simple virtual private network (VPN) and changing our location to the USA.

"When tickets for major matches are appearing on resale platforms at hugely inflated prices, it makes clear that the system simply isn't working for regular fans," said Dominic Rosso, chair of Chelsea Supporters Trust (CST).

"You can buy a seat in the same block I got mine for $470 (£346) on Vivid Seats. People are confused and upset that there is this clear conflict of interest.

"Mr. Boehly should be at the forefront of the fight against ticket touting in his role as chairman, but instead he is linked to a company charging eye-watering amounts of money."

Chelsea, the Football Association, and a representative for Boehly have been contacted for comment.

The FA Cup semi-final listings span all four stands, but are not the only Chelsea match for which Vivid Seats is offering tickets.

It has listings for all six of the Blues' final Premier League games of the season, with prices between $149 (£110) and $4,372 (£3,231).

And tickets are already available for the FA Cup final, priced at $452 (£334) and $4,912 (£3,630).

In practice, resale sites offering tickets at inflated values contributes to ticket touting and leaves genuine fans at risk of missing out altogether on tickets to some events.

CST contacted the Premier League last month to express concerns about Boehly's involvement with Vivid Seats, asking the league to consider whether the 52-year-old is in breach of competition rules.

In a letter of response, Premier League chief executive Richard Masters wrote: "Whilst we understand the concerns you have raised, based on the information currently available to us we are satisfied that Mr Boehly's involvement with Vivid Seats does not implicate a breach of Premier League rules and, as a result, we do not intend to take disciplinary action at this stage."

But the CST was not satisfied with the response.

"The Premier League has effectively acknowledged that its current rules do not address ownership links to secondary ticketing platforms, meaning this situation sits within a gap in the system," it said in an open letter to the club following Masters' explanation.

"While there may be no technical breach, that does not make the situation acceptable."

Last season, Chelsea ejected 1,393 people from Stamford Bridge for possession of touted tickets, while 2,740 accounts linked to touts were cancelled.

More than 350,000 attempted ticket purchases were blocked by their ticketing system.

If somebody trying to enter Stamford Bridge were found to be in possession of a ticket purchased at inflated value from Vivid Seats, they would in theory be refused entry, despite the ticket being purchased from a site in which the club's own chairman has a financial interest.

"Chelsea have invested a lot in ticket touting and we've worked closely with them on it," Ross added. "They have been cancelling touts' memberships and fair play to them, they're taking it seriously.

"But it undermines all that when people are still touting their tickets through a service linked to the chairman."

Last year, BBC Sport conducted an investigation exposing an enormous black market for tickets in the Premier League.

Re-selling tickets is illegal in the UK, but some companies are able to continue doing so using a loophole in the law.

Only companies based in the UK fall under the scope of the legislation, meaning platforms like Vivid Seats which are based abroad are able to sell tickets at inflated prices.

Vivid Seats and other platforms restrict sales in the UK, but British customers can often get around that by using a VPN service.

Platforms like Vivid Seats often display listings for tickets that haven't even formally gone on sale yet.

That is because customer orders are accepted and then attempts are made to source the required tickets afterwards, often via season ticket holders or members selling their tickets for more than they paid.

Buyers from resale platforms are then sent the tickets once they are sourced, or are typically given a refund if the order cannot be fulfilled.

Some of the companies still target UK customers using online ads, and use advanced software including 'bots' to hoover up tickets from official channels before reselling them at higher prices.