UEFA chief executive Lars-Christer Olsson says his organisation is prepared to clamp down on anyone who questions the integrity of officals in the wake of referee Anders Frisk’s resignation.

Frisk retired last week after receiving death threats from fans following criticism from Chelsea manager Jose Mourinho after the Champions League first knockout stage first leg against Barcelona.

Since the announcement there has been a war of words conducted between Mourinho and UEFA, whose referee committee chairman Volker Roth criticised the Chelsea manager for damaging football.

Olsson has issued a warning to players and coaches, reminding them of their responsibilities.

“We will not hesitate to take action against those not performing in a proper way.

“On the recent news of the retirement of Anders Frisk following personal threats, I would like to stress that coaches, players and managers have a responsibility…to protect the game itself,” he told delegates before the Champions League quarter-final draw on Friday.

Chelsea chief executive Peter Kenyon, speaking after the draw, told Sky Sports News: “We will not condone any action by our fans with regard to officials.

“Hopefully it is a situation we can now put behind us. We all want to get back to football.”