Louis van Gaal has been accused of making his Manchester United players too terrified to express themselves on the field.

In a withering attack on the Dutchman's management style, former United and England defender Paul Parker also accused Van Gaal of being "selfish" and inflexible.

United's style of play has been widely criticised this season, despite Van Gaal leading his side to within a point of the top of the Premier League table and the cusp of the Champions League knockout stage.

Six clubs have scored more goals than United's 20 in the Premier League this season, while Van Gaal has seen his team draw five of their last eight games in all competitions.

Former United players have been vehemently critical of Van Gaal's style this season: Paul Scholes admitted he would not want to play in the team, and Rio Ferdinand last week suggested his midfield offered "zero threat".

Other ex-players such as Roy Keane have been critical of Wayne Rooney's form up front.

Now Parker - who won two Premier League titles under Sir Alex Ferguson in the early 1990s - has added his voice to the debate surrounding Van Gaal's philosophy, accusing him of stifling United's more creative influences with his rigid tactics.

He said: "When Louis van Gaal arrived at United, I thought he too would be flexible. But we now have a situation where there are a lot of discontented players and we have to question why they are playing badly.

"I look at Anthony Martial and worry for him. He looks like a boy who doesn’t smile anymore. He doesn’t look like he’s enjoying himself. The form Memphis Depay is showing hasn’t just happened because he’s playing in the Premier League. That boy probably feels like a scapegoat.

"Ander Herrera is hugely popular with the fans because he makes things happen. Everyone loves to see players like that, but he’s barely playing and is probably unsettled. These players need freedom.

"Van Gaal puts the fear of God into players. It has to be his way. He selfishly manages the team. And no one enjoys it. He may be a successful manager, but he must learn – even at his age – to become a good man manager.

"At the moment we have to say he’s not man managing that team. All those players he’s got are not bad players, and they’ve not played negative football all their lives. He’s being incredibly stubborn."

Parker also suggested Van Gaal was showing favouritism to Rooney in refusing to drop him despite his poor form, which has yielded just two league goals this season.

"Under Van Gaal, every player who has had one bad game has been left out - except for Wayne Rooney," Parker added.

"He’s got to learn not to bear grudges. A player knows when they mistake, what they need is arm around them, not exclusion. What message is that sending out to the rest, other than: ‘that could be me’?"