The Premier League has written to Chelsea to seek clarification over the club's position with ticket resellers - amid controversy over Todd Boehly's involvement in Vivid Seats.

Boehly is both a director and investor in Vivid, described as an "unauthorised ticket seller" by the league, and also owns a 13% stake in Chelsea.

The website lists Chelsea matches on its platform, with some tickets last season at Stamford Bridge going for as much as £20,000. It is not allowed to operate in the United Kingdom, although it is permissible overseas.

Chelsea Supporters' Trust asked the Premier League to "act and investigate" the situation, which it believes is both a "breach of trust and "a clear conflict of interest" in an open letter issued in March.

Premier League CEO Richard Masters has explained it is discussing the matter with Chelsea in a situation described as "ongoing" at a Football Supporters' Association event last week.

The Supporters' Trust has also submitted evidence against the American company to the government's Department for Culture, Media and Sport (DCMS).

Boehly, Chelsea and Vivid have been contacted for further comment.

Vivid CEO Stanley Chia is quoted by Sportico , external as saying "economic and political volatility" has impacted the ticketing market as the company's share price fell by 61% this year.

Chelsea have recently pledged to take action on ticket touting, although without naming Vivid or other ticket resellers, which the CST letter said it was "encouraged" by.

There have been concerns about a "flat" atmosphere at Stamford Bridge, highlighted by previous manager Mauricio Pochettino and echoed by current head coach Enzo Maresca at times last season, amid trials of a singing section in the Conference League.

Chelsea are currently participating in the Club World Cup in the United States and next face ES Tunis in Philadelphia on Tuesday night.