Joel Glazer has told Manchester United fans he "cares deeply" about the club and has promised to prove it with investment both on and off the pitch.

The failed attempt to join the European Super League has triggered a new round of protest against the Glazer family ownership of the club, including at Old Trafford on Sunday which forced the postponement of the Premier League clash with Liverpool.

- Stream LIVE games and replays on ESPN+ (U.S. only)

Sources have told ESPN that further demonstrations are planned and amid rising tensions between the Glazers and supporters, Glazer has written to fan representatives to lay out a plan to quell the animosity.

"I want to reassure you that my family and I care deeply about Manchester United and feel a profound sense of responsibility to protect and enhance its strength for the long-term, while respecting its values and traditions," the letter issued on Friday read. "Our top priority is, and will always be, competing for the most important trophies, playing entertaining football with a team comprised of top-quality recruits and some of the world's best homegrown talent. Under Ole, we feel we are absolutely on the right track.

"Success on the field must be underpinned by solid foundations off it. We have supported sustained investment in the team over many years, and that will continue this summer.

"We recognise that we will need to significantly increase investment in Old Trafford and our training complex to ensure that the club's facilities remain among the best in Europe. As part of this, we will consult with fans on investments related to the stadium and the matchday experience."

One of the main criticisms levelled at the Glazers is a lack of communication with fans. Joel Glazer has given one interview with club media since assuming control of the club in 2005. The owners have vowed to put that right by becoming "better listeners" and allowing supporters to have a say in how the club is run.

"I want to acknowledge the need for change, with deeper consultation with you as our main fan representative body across a range of important issues, including the competitions we play in," Glazer wrote. "We also recognise the importance of fan and football interests being embedded in key decision-making processes at every level of the club, and we are open to constructive discussions on how to reinforce that principle.

"One of the clearest lessons of the past few weeks is the need for us to become better listeners. We believe in the principle of fans owning shares in the club. We have previously engaged with the Manchester United Supporters' Trust on fan share ownership and we want to continue and accelerate those discussions, together with provisions to enhance associated fan consultation.

"We recognise that the Government-initiated, fan-led review of football is a positive opportunity to explore new structures for fan engagement and influence. I can assure you that we will willingly and openly engage in the review, with the aim of putting fans at the heart of the game and ensuring their interests are advanced and protected."

The failed attempt to form the breakaway ESL has resulted in widespread protests from the six English clubs involved with United fans first breaking into the club's Carrington training ground to talk to manager Ole Gunnar Solskjaer, before groups of supporters made their way onto the pitch before the clash with Liverpool which forced the game to be postponed.

United fan groups have since announced they would boycott products belonging to sponsors affiliated with the club.