Manchester United co-chairman Joel Glazer says the club “apologise unreservedly for the unrest” caused by the proposed European Super League.

United, Liverpool and four other Premier League sides withdrew from the ESL on Tuesday after a backlash.

“We failed to show enough respect for its deep-rooted traditions,” Glazer said in an open letter to fans.

The 50-year-old admitted efforts “in seeking to create a more stable foundation for the game” did not honour the conventions of promotion and relegation within the wider football pyramid.

“For that we are sorry,” he said. “This is the world’s greatest football club and we apologise unreservedly for the unrest caused during these past few days.

“Manchester United has a rich heritage and we recognise our responsibility to live up to its great traditions and values.”

BBC Sport’s Simon Stone said: “It is rare indeed for Glazer to speak about United. He has done one interview with MUTV at the time of the takeover in 2005 – and that is it.”

Glazer said they will work to “rebuild relationships” across football “with a view to working together on solutions to the long-term challenges facing the football pyramid”.

“We also realise that we need to better communicate with you, our fans, because you will always be at the heart of the club,” he continued.

The Duke of Cambridge, who is president of the Football Association, said in a tweet that he is pleased that football supporters’ opposition to the ESL had been “heard and listened to”.

Earlier on Wednesday, Henry took sole responsibility for the “unnecessary negativity”, saying: “In this endeavour I’ve let you down.

“The project put forward was never going to stand without the support of the fans.

“Over these 48 hours you were very clear that it would not stand. We heard you. I heard you.”

In other developments on Wednesday:

• Juventus chairman Andrea Agnelli admitted the project could not proceed after the Premier League clubs withdrew.
• AC Milan, Inter Milan and Atletico Madrid followed suit, taking the total withdrawals to nine.
• Rival managers, chairmen and officials called for tighter regulations and possible punishments for the six English clubs.

Before Liverpool’s statement confirming the club’s withdrawal, captain Jordan Henderson had said on social media his side’s “collective position” was that they did not want the breakaway to go ahead.

“We don’t like it and we don’t want it to happen,” read a message that was also posted by many fellow Liverpool players.

Reds manager Jurgen Klopp and midfielder James Milner also voiced their opposition to the plans after their Premier League game at Leeds on Monday.

In a video released by Liverpool, Henry also apologised to Klopp, the players and chief executive Billy Hogan, promising to do all he could to win back the supporters’ trust.

“They have absolutely no responsibility for this disruption,” added Henry. “They were the most disrupted, and unfairly so. This is what hurts most. They love your club and work to make you proud every single day.”

“Again, I’m sorry, and I alone am responsible for the unnecessary negativity brought forward over the past couple of days. It’s something I won’t forget. And shows the power the fans have today and will rightly continue to have.”

‘Uefa need to stop pandering to these people’

In a statement, Liverpool supporters group Spirit of Shankly said Henry’s apology was a “PR exercise” that was “too little, too late”.

“We need a fundamental change in football governance,” it added. “One that is fair for the whole football pyramid, not just the rapacious elite.”

Crystal Palace chairman Steve Parish called the ESL plans an “attempted coup” and said the authorities should now stand up to any club pushing for favourable treatment.

He told BBC Breakfast: “What Uefa need to do is start looking after the game and stop pandering to these people and trying desperately to keep them inside the tent because they’re going to be inside the tent now whatever happens.”

Brighton chief executive Paul Barber told BBC Radio 4’s Today programme that the rules needed to be “tightened significantly” to make sure this never happened again.

When asked whether the six English clubs should be punished with points deductions, he added that was “certainly something the Premier League and Football Association need to look at”.

West Brom manager Sam Allardyce said the idea of a Super League had merely been put on hold and without “better protection” we would see similar proposals “again and again”.

Former Liverpool winger John Barnes went as far as suggesting a salary cap needed to be introduced to ensure “a level playing field” for every team in the Premier League.