LONDON (DPA) - The video assistant referee (VAR) has missed four calls over the opening four matches of the Premier League season, referees' chief Mike Riley said on Thursday (Sept 12).

The league's first season using VAR has seen a total of 227 decisions involving goals, red cards and offsides reviewed so far, with six being overturned.

According to Riley, four more should have been changed but were not.

Among them was a goal by Newcastle's Fabian Schar which should have been disallowed for handball and the failure to show Leicester's Youri Tielemans a red card for stamping on an opponent.

Two other decisions not to award penalties for fouls on Manchester City's David Silva and West Ham's Sebastien Haller were also wrong.

"We are learning as we go along and we are constantly improving," Riley, the general manager for Professional Game Match Officials Limited, told Sky Sports.

"There were four incidents where VAR didn't intervene and had they done, we would have a better understanding of the role VAR plays in the game.

"(The mistakes) are all about the judgement of VAR and the process that we adopt.

"These are examples where VAR could have had a benefit and intervened to help the referee on the day."