A Liberal Democrat letter demands Andy Burnham Manchester City owners disclosures: details of every meeting and conversation since his time as mayor, and a declaration of all the hospitality he has accepted at the Etihad Stadium.

The disclosure Sabine is demanding

The demand was set out in a strongly-worded letter from Anna Sabine, the Liberal Democrats' culture, media and sport spokesperson. It asks Burnham to come clean about his dealings with the club's owners, and it reaches back to his time as mayor.

• •Details of every meeting and conversation with City Football Group, the Abu Dhabi United Group (ADUG) or UAE government representatives
• •Any hospitality freebies he received over the same period
• •A declaration of all the hospitality he has accepted at the Etihad Stadium

Why the Liberal Democrats are pressing

Burnham was widely criticised this week for saying he would be "really concerned" if ADUG were forced to sell City. The criticism followed City being found guilty of breaching the Premier League's financial regulations, and Downing Street issued two clarifications of his position on Thursday.

In the letter, Sabine called his apparent defence of the club "extraordinary", noting his response had been to thank the owners for their work and describe the findings as "contested" and "wrong to jump to a conclusion". A prime minister, she argued, should not use his position to call the findings into question and risk undermining trust in the Premier League's processes.

The letter also sets out the verdict's scale: an independent commission found Manchester City guilty of 114 charges of breaching financial rules across a timeframe of nearly a decade, including "sham contracts" and schemes to disguise more than £830m of funding. It adds that this has been a difficult year for football's reputation: Fifa's conduct around the World Cup has already raised serious questions about integrity, and the letter invokes Gianni Infantino's aborted World Cup sell-off scheme.

Nine years of ties to City's owners

Burnham had close relations with ADUG, the company through which Sheikh Mansour bought City in 2008, and has praised ADUG's investment in Manchester. He served nine years as mayor of Greater Manchester, a role that ended when he returned to parliament this summer.

His matchday attendance forms part of that picture:

• •Pictured at City games in the Etihad Stadium's hospitality areas
• •An Everton fan, accommodated in the directors' box at two Everton matches at Hill Dickinson Stadium despite holding a season ticket in the South Stand
• •He has not attended a City game since he became prime minister

The extent of the Etihad hospitality is unclear, because under Greater Manchester Combined Authority regulations the public disclosure of gifts is available for current office holders without a freedom of information request.

The appeal and the next letters

Manchester City said on Friday they had appealed against the independent commission's verdict, and repeated their assessment of the ruling:

Sabine said Burnham's ties to ADUG should be scrutinised: fans, she wrote, expect their prime minister to stand up for the rules in place, not to appear to side with a club found guilty of breaking them. When the prime minister leaps to the defence of a club's owners within hours of a verdict, people are entitled to ask what their relationship is. Sabine wrote:

She now plans to write to Downing Street and the Greater Manchester Combined Authority to demand details of their meetings with Burnham.