Manchester United manager Louis van Gaal has left the Premier League club, he said in a statement on Monday.

"I am very disappointed to be unable to complete our intended three-year plan," he announced on the United website.

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

Former Chelsea and Real Madrid manager Jose Mourinho will be named as Van Gaal's replacement this week, British media have reported.

Van Gaal led United to victory in the FA Cup final on Saturday after they finished fifth in the Premier League and failed to qualify for next season's Champions League.

"I am immensely proud to have helped United win the FA Cup for the 12th time in the club's history," said Van Gaal.

"I have been privileged during my management career to have won 20 trophies but winning the FA Cup, which is steeped in so much history, will always be one of the most special achievements of my career.

"I hope that winning the FA Cup will give the club a platform to build upon next season to restore the success that this passionate set of fans desire," he added.

The 64-year-old Dutchman signed a three-year contract at Old Trafford in May 2014, succeeding David Moyes, who took over from Alex Ferguson for the 2013-14 season.

Van Gaal lifted the club from seventh place in the league under Moyes to fourth in his first season but despite further heavy spending in the transfer market the team have stagnated and the fans have become increasingly disgruntled.

United's inability to produce the free-flowing football that characterised Ferguson's trophy-laden reign at Old Trafford has been Van Gaal's biggest failing.

The team's goals per game ratio, especially at home, last season was lower than all their main rivals.

United briefly topped the table at the end of September, but by mid-December they had dropped out of the top four after humiliating back-to-back defeats by promoted clubs Bournemouth and Norwich City.

Failing to qualify for the knockout stage of this season's Champions League, after finishing third in their group behind VfL Wolfsburg and PSV Eindhoven, was another damaging blow for Van Gaal.

Losing to arch-rivals Liverpool in the Europa League increased the pressure on the former Ajax Amsterdam, Barcelona, Bayern Munich and Netherlands coach.

Amid regular media reports that Portuguese coach Mourinho was poised to replace him, Van Gaal steered United to the FA Cup final with wins over West Ham United and Everton.

They came from behind to beat Crystal Palace 2-1 after extra time in the final at Wembley to win their first major trophy for three years but it was not enough to save Van Gaal.

"It has been an honour to manage such a magnificent club as Manchester United FC, and in doing so, I have fulfilled a long-held ambition," said Van Gaal in Monday's statement.

"Thank you to the owners and board of Manchester United for giving me the opportunity to manage this great club."