UEFA chief refereeing officer Pierluigi Collina has reminded officials of their responsibility to player safety after Luke Shaw's nasty leg break.

A little more than three weeks have passed since the 20-year-old left-back's fine start to the season was brought to an abrupt halt in Manchester United's Champions League clash against PSV Eindhoven.

Shaw suffered a double leg break in a tackle by Hector Moreno, leading to two operations and a lengthy spell on the sidelines that could end extinguish his Euro 2016 hopes.

Collina found it "tough'' it to watch and was disappointed by the reaction of referee Nicola Rizzoli as well as the players.

"If you see the clip in PSV v Man United when Shaw was heavily injured and [had his] leg broken, the defender played ball and legs,'' the UEFA refereeing chief said, speaking at the Leaders in Sport Business Summit 2015.