Unai Emery's men collapsed at Camp Nou and allowed Barca to complete an unlikely comeback to advance 6-5 on aggregate but PSG believe Luis Enrique's side were aided by a number of dubious decisions from the German official.

Marca reported that PSG had submitted an official complaint to UEFA president Aleksander Ceferin, listing various controversial decisions made by Aytekin during the French champions' ill-fated second leg in Catalonia.

A source close to Les Parisiens has since told ESPN FC that the letter does exist and has been dispatched to the European football governing body.

Paris Saint-Germain were unable to hold on to a four-goal advantage from the first leg of their game against Barcelona.

While accepting their defeat over the two legs, PSG's document is said to list Luis Suarez's alleged dive for a second penalty and Javier Mascherano's foul on Angel Di Maria -- which the former later admitted to -- as two of the main concerns.

A penalty not given for Mascherano's first-half handball, Gerard Pique not receiving a second yellow card, Thomas Meunier's foul on Neymar for Lionel Messi's goal from the penalty spot and a Neymar foul on Marquinhos have also been included.

Aytekin's performance has been pored over by French and Spanish press alike and a petition has even been compiled to get the fixture replayed because of the German official's perceived lack of control over proceedings.

PSG coach Emery said his team "lost everything" because of Aytekin's decisions late in the match, while chairman and CEO Nasser Al-Khelaifi tried to avoid making excuses but did feel his team were denied "two penalties."