Soccer's video assistant referee (VAR) has achieved 98.9 per cent accuracy and not been called on for two-thirds of matches since its introduction in March 2016, an independent report has found.

During last season, the A-League became the first top-level domestic league in the world to implement the technology.

But there was outrage among players, coaches and supporters at times due to lengthy delays and poor application of the guidelines.

It prompted a recent tweaking which led to fewer interventions.

A study by a Belgian university, Katholieke Universiteit Leuven, has found surprising results.

Of 804 matches in more than 20 competitions since the VAR experiment began in early 2016 — a further 700 friendly and exhibition matches were not considered — it was not called on in 533, and just 42 matches had more than one review.

In those games, there were 3,947 checks for possible reviewable incidents, most being done in the background without interfering with games.

Despite Australian frustration over review times, the study found the median review times was just 60 seconds and lost playing time was minimal, at less than 1 per cent of match time.

To put that in perspective, free kicks saw 9.5 per cent of playing time lost, throw-ins 8 per cent and substitutions 3.5 per cent.

The Belgian research found a VAR accuracy of 98.9 per cent compared with 93 per cent for decisions before the new technology was used.

It concluded a 100 per cent accuracy would be impossible due to human perception and subjectivity.

The International Football Association Board made public the findings at its annual business meeting this week.

The VAR is intended to give on-field referees guidance on goal scoring, penalties, direct red cards or mistaken identity.