LONDON -- Eric Harrison, the Manchester United youth team manager who launched the career of David Beckham as part of the renowned group of "Class of 92" players, has died. He was 81.

United said Harrison died Wednesday but did not provide a cause of death. He was diagnosed with dementia four years ago.

"Eric's contribution to football and not just at Manchester United was incredible," said former United manager Alex Ferguson, who led United from 1986-2013 and remains a club director. "... He built character and determination in those young players and prepared them for the future."

Harrison's 1992 Youth Cup winners formed the backbone of the team that dominated the Premier League for two decades under Ferguson. Alongside Beckham, Harrison's graduates included Ryan Giggs, Paul Scholes, Nicky Butt and the Neville brothers, Phil and Gary.

The six players signed a tribute written to Harrison that was posted on Beckham's Instagram account on Thursday.

"We've lost our mentor, our coach and the man who made us," Beckham's statement read . "He taught us how to play, how to never give up, how important it was to win your individual battles and what we needed to do to play for Manchester United Football Club. ... He made us understand how to work hard and respect each other and not just on the pitch. We won't forget the life lessons he gave us. Eric, we love you and owe you everything."

Queen Elizabeth II honoured Harrison's contribution to the game last year when she made him a Member of the Order of the British Empire, or MBE.

Beckham became one of the most famous athletes on the planet, captaining England and playing for Real Madrid, the Los Angeles Galaxy, AC Milan and Paris Saint-Germain.

"I can still hear him telling me NO MORE HOLLYWOOD PASSES," Beckham wrote. "I can still see him as we played on The Cliff training ground looking down on us either with a proud smile or a loud bang of his fist on the window knowing any minute he would be on his way down to probably advise me in the most polite way to stop playing those passes."

Giggs and Scholes were still in the squad when United collected its record-extending 20th English title in 2013 as Ferguson retired.

"He was a teacher. He gave these players a path, a choice and he only did that through his own hard work and sacrifice," Ferguson said. "He was able to impart that education to the young, which made him one of the greatest coaches of our time. On a personal level, Eric had a wicked dry sense of humour and was straight talking, and I admired that in him."

Phil Neville, who has forged his own coaching career leading the England women's team, remembered Harrison as "our second father."

"He didn't prepare you for a life in football, he prepared you to actually succeed in life and the values he instilled into us -- an unbelievable work ethic, the toughness of his attitude, the attention to detail," Neville told the BBC. "He would not let you get away with absolutely anything, on and off the pitch.

"The way you spoke to the canteen ladies, the kit man, the way you dressed, your timekeeping -- they were values that stood us in good stead for all our lives."

The Class of '92 remains united through its ownership stakes in fifth-tier club Salford City .