PARIS (AFP) - Football's most powerful clubs faced mounting calls for reprisals over the European Super League fiasco on Thursday (April 22), as the rebel competition's boss insisted it was merely "on standby" despite nine teams pulling out, although Uefa president Aleksander Ceferin said next week's Champions League semi-finals were unlikely to be affected.

Super League chief Florentino Perez, president of Real Madrid, complained about the "aggression" prompted by the breakaway league, which folded just 48 hours after its unveiling following blanket opposition from fans and officials.

Manchester City, Manchester United, Arsenal, Liverpool, Tottenham Hotspur and Chelsea withdrew on Tuesday, followed by Atletico Madrid, Inter Milan and AC Milan on Wednesday.

It leaves just Barcelona and Perez's Real Madrid, along with Italian champions Juventus - who admitted the lucrative project could not now go ahead.

Premier League leaders City are due to play Paris Saint-Germain, conspicuous by their absence from the Super League plans, in the first leg of the Champions League semi-finals on April 28, a tie Ceferin expects to go ahead as scheduled.

Record 13-time winners Real face Chelsea in the other last-four clash.

"There is relatively little chance that next week's matches will not be played," Ceferin told Slovenian television Pop TV.

"The key thing is that the season has already started. If we cancelled the matches, television stations would have compensation demands."

He struck a conciliatory tone on Wednesday, saying he wanted to "rebuild the unity" of European football, and described the English clubs as "back in the fold".

Meanwhile, Manchester United fans breached security at their club's training ground on Thursday as they protested against the Glazer family for the owners' role in the failed breakaway league.

United manager Ole Gunnar Solskjaer was forced to speak to around 20 supporters after they blocked both entrances to the Carrington headquarters.

The protestors unfurled banners that read "51% MUFC 20", "We decide when you play" and "Glazer out".

'Football belongs to the fans'

He believes the rapid and passionate response fans of Premier League clubs played a key role in convincing the owners to back down.

"This has given big lessons and it shows the importance of football in the world," the Spaniard said.

"It shows that the soul of this sport belongs to the fans."

City boss Pep Guardiola called the controversy a "closed chapter" following his side's 2-1 victory at Aston Villa.

"I think everyone who loves football didn't support this Super League, including players at our club," City captain Fernandinho told Sky Sports.

"We are so happy now because everything was turned around and all the people who love football are calm.

Despite the tournament's swift demise, Perez was defiant, saying: "The project is on standby. The project exists."

"I am sad and disappointed. We have been working on this for three years and fighting against the financial situation in Spanish football," added Perez, in an interview with Spain's Cadena Ser radio.

"I have never seen aggression like it, from the president of Uefa and some presidents of the national leagues.

"It seemed orchestrated, it surprised all of us. It was like nothing I've seen in my career, like we had killed football. We were working on how to save football."

The clubs apologised to their fans for joining the ill-conceived, JPMorgan-backed league, which drew accusations of greed and a lack of respect for football's traditions.

The powerhouse clubs, saddled with huge debts and wage bills, stood to share billions from the annual league, where they were guaranteed entry each year.

But they quickly backtracked following strident objections from European and world bodies Uefa and Fifa, threats of legal action and protests by fans.

'Time to get vindictive'

Uefa's executive committee will decide whether to punish the "dirty dozen" at its next meeting on Friday, said its Swedish vice-president Karl-Erik Nilsson.

"It's already had consequences one way or another, with the shame they have to live with now," he told football website Fotbollskanalen.

"There will be consequences in their own organisations, and whether there will be further consequences is something we need to discuss."

Supporter groups are calling for "real change" at their clubs, whose foreign owners are often seen as aloof and out of touch with fans.

"The Super League is dead. Now we need to work with government to change how English football clubs are owned," said the Arsenal Supporters' Trust, while the Spirit of Shankly accused Liverpool owner John Henry of "crocodile tears".

"This debacle must be a catalyst for real change, not an exercise in damage limitation," the fan group said.

Guardian columnist Jonathan Liew said it was "time to get vindictive".

"Points deductions, suspensions, expulsions, eye-watering fines, transfer embargoes: none of this should be taken off the table at this stage," he wrote, suggesting a two-year ban from European competition for all 12 clubs.

Perez, insisting work was continuing to salvage the Super League, blamed an unnamed English club for sowing seeds of doubt, and accused Uefa of being overly dramatic.

"There was someone in the English group, who didn't have much interest in the Super League," he said.

"And they started infecting the rest. They all signed a binding agreement but in the end because of the Premier League avalanche, they said 'hey, we're off'."

He added: "Uefa put on a show. They made it look like we dropped an atomic bomb. They haven't let us explain.

"It can't be that those at the top lose money and the rest earn money. The rich now lose a lot of money."