Lionel Messi would cost Manchester City half a billion pounds if they went ahead with what would be the biggest signing in Premier League history before the start of the season.

City were thought to be considering a sensational swoop for Messi after he handed in a transfer request at Barcelona and demanded to be allowed to leave for nothing this summer.

But Barca were refusing to honour a break clause in his contract which expired in June and which left him facing paying a euro 700 million (£631.3 million) buyout clause to walk away.

The club were reportedly holding out for a world-record £200 million fee for their greatest player, who earns around £100 million a year in wages and bonuses.

City were weighing up offering Messi a long-term contract that would see him play for them for three years, before moving to sister club New York City FC, as well as giving him the chance to become an ambassador for parent company City Football Group.

That would cost them £500 million in total, unless Barca could be made to budge on their asking price or Messi took a pay cut.

City declined to comment on what the club view as speculation linking them to the 33-year-old.

Bartomeu’s stand

According to reports in Spanish media, club president Josep Maria Bartomeu is willing to resign if Messi changes his mind and decides to stay.

Another report said Messi plans to go to the club’s training complex on Sunday to take the relevant PCR tests, which all of the squad will be subjected to.

He also intends to train the next day, under Ronald Koeman, in what will be the coach’s first training session.