Former Manchester United manager Louis van Gaal has claimed many of his stars were 'unprofessional' during his time in the Premier League.

It was hoped Van Gaal would resurrect the Red Devils following the failure of Sir Alex Ferguson's replacement David Moyes, though his tenure was short lived.

The Dutchman tried to incorporate his meticulous approach at United, sending around personal emails to each of his players detailing their progress ahead of face-to-face meetings.

Louis van Gaal has claimed many of his Manchester United players were 'unprofessional'

The Dutchman felt let down by players who would only pretend to read his progress emails

Van Gaal attached alerts to these emails so he would be notified whether or not a player opened his message, though he concedes that some individuals did try to dupe the system and make out as though they had read his feedback.

'I developed the digital tracker with my IT man. Each player was able to log in,' Van Gaal revealed this week in an interview with German publication Bild.

'So I gave everyone the opportunity to prepare for the conversation with me at home and to meet me in dialogue at eye level.'

When asked about players not bothering to read his messages, Van Gaal was forthright.

Van Gaal wished some of his 'unprofessional' United players were more like Arjen Robben

'That’s true, too. But this testifies to their unprofessionalism and I have then addressed them.

'But I already did that with the emails at Bayern. My conviction is that a full professional also wants to live professionally. Like Arjen Robben. He read the emails.'

In a series of revelations, the former Holland manager admitted he tried all he could to bring prolific forward Robert Lewandowski to Old Trafford.

United fans will be accustomed to their team having been linked with Thomas Muller for the past several seasons, but Van Gaal has admitted it was his Bayern Munich strike partner that he wanted to sign.

The Dutchman has hailed Lewandowski as the complete striker and the best in the world at what he does, but admits Bayern would not allow their prized asset to leave at any cost.

'He is currently the best striker in the world. I also wanted to train Lewandowski and wanted to bring him to Manchester United,' Van Gaal added.

Van Gaal has also revealed he tried all he could to bring Robert Lewandowski to Old Trafford

An FA Cup final victory against Crystal Palace was to be Van Gaal's final act as United manager

'The price was not a problem for Manchester United, but Bayern did not want to let him go.'

United parted ways with Van Gaal in May 2016, while the 66-year-old was just two years into a three-year contract.

The Dutchman's deal, reported to have been worth around £6.4million per year, was mutually cancelled by the club and manager.

Van Gaal's final game in charge of the Red Devils was an FA Cup final victory over Crystal Palace, before he was promptly replaced by current boss Jose Mourinho.