Manchester United have written a letter of protest about the incidents to the Lisbon-based side and have called on European football governing body UEFA to take action, Britain's Sun newspaper reported Saturday citing a club source.

Defender Patrice Evra and striker Louis Saha as well as midfielder Kieran Richardson and defender Wes Brown were all targeted by the Portuguese club's supporters in the Group F 1-0 win, the paper reported.

"I didn't notice anything in the place where I was and I don't recall Benfica fans being accused of such acts," said Santos in comments published Monday in daily Portuguese newspaper A Bola.

"Will we be punished? These things have to be proven. We'll see if this is true. It doesn't worry me," he added.

UEFA were waiting for reports from the match delegate and the referee before deciding whether to follow up the complaint, the British newspaper report said.

If found guilty Benfica could be hit with a heavy fine or ordered to play one or more games behind closed doors.