UEFA: Coaches support extra-ref experiment
However, they are less enthusiastic about changing the away goals rule used in European club competition, even though some feel it encourages teams to play defensively at home rather than attack when they are away.
The new refereeing system, which features one extra linesman behind each goal, was first tried in the Europa League last season and has been extended to the Champions League and the Euro 2012 qualifiers.
UEFA president Michel Platini is one of the most vociferous supporters of the experiment which is being carried out in other competitions worldwide over the next two years before FIFA decides whether to implement it on a permanent basis.
"They're very positive about this experiment," UEFA's technical director Andy Roxburgh told reporters after a two-day meeting of some of Europe's leading coaches at UEFA headquarters including Pep Guardiola, Alex Ferguson, Jose Mourinho, Claude Puel and Felix Magath.
"They're very much aware of the problems of going down the technology route and, like Platini, they would like to keep it human if possible, so this experiment with the additional referees allows us to do that."
"The additional refs sometimes do not always look very active but they are very active because they are in constant touch with the referee," added Roxburgh.
"This role is new so it's something which has to be nurtured and developed and it will evolve.
"There's also the deterrent effect, if there's eyes behind the line there might not be so much pulling in the penalty box or simulation."
The five referees failed one test last week when officials at the Tottenham v Young Boys Champions League qualifier missed an obvious handball by Jermain Defoe before he scored a Spurs goal.
"There's no 100 percent guarantee but this is an attempt to make it better, to minimise mistakes," said the former Scotland manager.
Roxburgh said coaches had shown little enthusiasm for changing the away goals rule.
"We raised the question that, after 40 years, is it something that should be reviewed because some teams seem to think now that a 0-0 at home is a good result because they didn't lose an away goal, so has the balanced changed a bit?
"But they think that after 40 years, it's well established, part of the game and we should leave it.
"However, they were questioning whether we should have the away goals rule in extra-time," he added.