FIFA is interested in the possibility of using video assistant referees (VARs) at the 2018 World Cup, the technical director of the International Football Association Board (IFAB) has told The Times.
Former Premier League referee David Elleray, who now works as the IFAB's technical director, said improvements had been made over the course of the trials and that FIFA is now open to the idea of using the system at next year's World Cup.
"So far we are very happy with how the tests have gone and the fact that so many of the major footballing countries want to be part of the experiment shows we are moving in the right direction," he said. "It has so far worked better than a lot of people have anticipated.
"If the trials go well, FIFA would like to have the option to use it for the World Cup next year. England are also following this closely and may well become part of it in the future."
Off-line experiments have taken place in the Premier League, while trials in Germany have been so successful that the system is to be introduced into the Bundesliga from next season, allowing the extra official to monitor matches and intervene in the following situations: irregularities in the case of a goal decision; penalty box situations regarding penalty calls; red card offences unnoticed by the referee; and in cases of mistaken identity over a yellow or red card.
In other trials, referees have been allowed to use the technology pitch-side to review their own decisions.
There has been criticism that the system can lead to delays in the action, most notably after Real Madrid's 2-0 victory over Club America at the Club World Cup.
Cristiano Ronaldo scored the second goal in that game but it was initially disallowed by Paraguayan referee Enrique Caceres, who thought the VAR had advised him that it was offside. The game appeared to have restarted before the players were called back and the replay was reviewed.
Elleray said the confusion arose because the VAR had not realised his microphone was live when talking to a colleague and that Caceres had mistakenly believed he was being advised that the goal was offside.
"We have changed the protocol so the VAR has to actually press a button on the microphone when he wants to speak to the referee," Elleray said. "That is what these tests are for -- to flag up potential problems.
"In terms of correcting unfairness, nothing else will be able to do that and that is the attraction for most people."
The IFAB confirmed this week that it will discuss the success of the VAR trials when its annual general meeting takes place on March 3.