April 25 (Reuters) - Hundreds of Manchester United supporters gathered outside Old Trafford on Saturday to demonstrate against the Glazer family's ownership after the club was involved in plans to join the now-failed European Super League, British media reported.

Manchester United were among six Premier League clubs who signed up for the breakaway league before withdrawing on Tuesday amid a storm of protest from fans, players and the British government.

The club was bought by the American Glazer family for 790 million pounds ($1.1 billion) in 2005. Although it has been listed on the New York Stock Exchange since 2012, the Glazers retain majority ownership.

Club supporters assembled by the Trinity Statue outside the ground on Saturday and set off yellow and green flares - colours synonymous with fan protests against the Glazer family, the Manchester Evening News reported.

Protest signs read "United against greed" and "Glazers out", according to Sky Sports.

Manchester United executive vice-chairman Ed Woodward, one of the leading figures in the breakaway project, said on Tuesday he would step down from his role at the end of 2021.

Liverpool, owned by Fenway Sports Group and another of the English clubs involved in the Super League, also saw around 150 fans protest on Saturday before a match with Newcastle United.

Banners saying "Enough is enough, FSG out" and "Our game, our club: thanks but no Yanks" were unfurled outside Anfield. American owner John Henry has apologised for the club's involvement in the project.

Manchester United, who are second in the Premier League, visit Leeds United later on Sunday.

($1 = 0.7209 pounds) (Reporting by Shrivathsa Sridhar in Bengaluru; Editing by Edwina Gibbs)