Britain's government vowed on Monday to do "whatever it takes" to protect football, raising the possibility of invoking competition law to block a proposed new European Super League by breakaway clubs.
Culture and Sports Secretary Oliver Dowden said he held urgent talks with heads of the Premier League, English FA and Uefa.
"Our message to them was clear: they have our full backing," Mr Dowden told Parliament, pledging a "very robust response".
"But be in no doubt, if they can't act we will. We will put everything on the table to prevent this from happening."
Six English Premier League clubs are part of the breakaway bid, along with three teams each from Italy and Spain.
Mr Dowden said the English clubs could find themselves subject to a formal review under British anti-trust law, which prevents the formation of monopolies or corporate cartels.
The government was also examining reform of clubs' governance, to look at their finances and the possibility of an independent regulator for football, he said.
The government also formally announced the much-delayed launch of a fan-led forum to investigate the future of football in Britain.
Ideas in the mix include emulating the model in Germany of fans enjoying majority control at their clubs.
"Put simply, we will be reviewing everything the government does to support these clubs to play," Mr Dowden said. "We will do whatever it takes to protect our national game."
Earlier, Prime Minister Boris Johnson reaffirmed his strong opposition to the plans announced late on Sunday by Manchester City, Liverpool, Arsenal, Chelsea, Tottenham and Manchester United.
"We are going to look at everything that we can do with the football authorities to make sure that this doesn't go ahead in the way that it's currently being proposed," Mr Johnson said.
The six English teams are more than just "great global brands", he said.
"They're also clubs that have originated historically from their towns, from their cities, from their local communities.
"They should have a link with those fans, and with the fan base in their community. So it is very, very important that that continues to be the case."
