Deco believes the crisis facing Spanish referees has been caused by the technology's introduction.
He told Sport: "Refereeing errors have always existed, because it's a human thing. The only thing I'm not clear about is how the VAR is helping . What has it improved? Surely some things have, but we're still controversial... I get the feeling that the VAR has made the situation worse: there are more discussions, more debates, more suspicions...
"There are a number of more complicated things. We need to open a debate on this issue. In theory it has to be something to improve, but I don't really see how much it helps," said the Portuguese.
Deco also had a word on handling the press.
He said, "What worries me and I will not allow is for them to lie or make things up. Or to go into personal matters. But everything that has to do with my work, being criticised is normal. It is part of football.
"The only thing missing would be for me to come to Barça and think that people could not criticise my decisions. The problem is that many do not do it impartially or correctly."