Louis van Gaal's sacking as Manchester United manager was finally confirmed on Monday, as the Premier League club announced the Dutchman had left with immediate effect.

Van Gaal had appeared certain to lose his job since reports leaked out after United's FA Cup final victory against Crystal Palace on Saturday that former Chelsea boss Jose Mourinho was being lined up to replace him.

The 64-year-old had hoped leading United to their first major silverware since the retirement of legendary boss Alex Ferguson in 2013 would persuade the club's United States-based owners, the Glazer family, to let him see out the final season of his three-year contract.

But United's failure to qualify for the lucrative Champions League proved fatal to van Gaal's chances of survival.

Van Gaal felt he was hard done by after United suffered injuries to several key players and he couldn't hide his anguish at his premature exit.

"I am very disappointed to be unable to complete our intended three year plan," van Gaal said in a statement released by United.

"It has been an honour to manage such a magnificent club as Manchester United, and in doing so, I have fulfilled a long held ambition.

"I believe that the foundations are firmly in place to enable the club to go forward and achieve greater success."

United's statement added "a decision on a successor as manager will be announced soon" as vice-chairman Ed Woodward praised van Gaal's efforts.

"I would like to thank Louis and his staff for their excellent work in the past two years culminating in winning a record-equalling 12th FA Cup for the club (and securing him a title in four different countries)," Woodward said.

"He behaved with great professionalism and dignity throughout his time. He leaves us with a legacy of having given several young players the confidence to show their ability on the highest stage.

"Everyone at the club wishes him all the best in the future."