Two extra assistant referees will used in next season's UEFA Champions League final qualifying round and Euro 2012 qualifiers as UEFA extended its five-referees experiment. The Europa League, which experimented with the five-ref system last season, will continue it as well.

The system adds two extra linesmen, one behind each goal, to help referees spot penalty area infringements and determine whether the ball has crossed the line.

"We have made this experiment in the Europa League and it went well," said UEFA general secretary Gianni Infantino. "Something else must be done to help the referees, you add eyes and you help the referee to cover their ground in a much better way.

"It's difficult to find anything negative in this experiment, although it will have to evolve, for example how shall they move, where do they have to be placed? But first results were positive and we want to do something for the good of soccer."