Pierluigi Collina, the chairman of the FIFA Referees Committee, has warned of a global shortage of match officials if efforts are not made to tackle abuse and violence towards referees at the grassroots level.

Collina, who was in charge of the 2002 World Cup final between Brazil and Germany, said it is a "real threat" when match officials face verbal and physical abuse in amateur football.

"It's a worldwide problem that we need to consider and we need to take (action) as soon as possible," Collina told Sky Sports.

"We have a huge number of referees working every weekend in grassroots and amateur football. At this level there is something as a threat; it's a physical threat of violence.

"Unfortunately, at this level, instead of paying huge respect for these unknown heroes... they are abused verbally, physically sometimes, this is a real threat."

Collina welcomed initiatives to improve behaviour towards the officials.

"Many national associations have launched a campaign, the FA did something like this, also UEFA and FIFA are promoting respect, not only towards referees but football," the 57-year-old Italian added.

"I know that it won't be easy but something has to be done. Certainly top football has to give grassroots football the correct message."