The Catalans were held to a scoreless draw in the first leg of their quarter-final on Wednesday, after which players such as Xavi, Lionel Messi and Javier Mascherano, as well as coach Pep Guardiola, complained about the poor state of the pitch.

"FC Barcelona has lodged a complaint with UEFA over the state of the pitch at the Giuseppe Meazza (San Siro) stadium during the Champions League match," the club announced on its website.

Barcelona brought up the issue during the post-game meeting with UEFA representative Mikalai Varabyov.

Varabyov has submitted his version of events to European football's governing body, and UEFA is now expected to ask Milan for an explanation.

The return leg takes place at Camp Nou on Tuesday.