Uefa is awaiting the official report from Manchester City's Europa League victory at Porto before deciding whether to act on the club's complaint that Mario Balotelli was racially abused by a section of the home support.

The Uefa match delegate, Joti Chatzialexiou, has to file his account within 48 hours of the game, meaning the governing body may not receive it until late on Saturday afternoon. Given the ongoing problem of racism in some areas of continental Europe and the incidents that have marred English football this season, it seems almost certain that Uefa will investigate what occurred at the Estádio de Dragão on Thursday evening.

After what sounded like monkey noises being directed at Balotelli and Yaya Touré during the first half of the 2-1 win in the opening leg of the last-32 tie, the forward was then subjected to racist abuse when replaced by Sergio Agüero in the 77th minute and City made an official complaint to Chatzialexiou. The striker told club officials that he had heard monkey noises.

A Uefa spokesman said: "We are aware of Manchester City's claims and we are still waiting for the official report from the match delegate. That usually arrives one or two days after the match. The procedure then is if something like this is included in the report, then our disciplinary unit will have a look at it and decided if a case needs to be opened."

In November of last year Uefa's control and disciplinary body fined the Bulgarian Football Union €40,000 after the Football Association complained of racist chanting by home fans during England's 3-0 Euro 2012 group win at the Vasil Levski stadium.

On Friday Porto defended themselves against the racism accusations. "What we can basically say is that nothing abnormal happened, no one noticed anything strange, not even the Uefa delegates that worked closely with Porto during the match," the Porto spokesman Rui Cerqueira told Reuters.

He went on to describe two chants from Porto and City fans in support of their respective players Hulk and Sergio "Kun" Agüero that could have been mistaken for other sounds. "Kun, Kun, Kun; Hulk, Hulk, Hulk," he said, demonstrating the chants. "[Those chants] can be easily confused with racist chants."

He also said Porto had no record of previous racism. "We are very proud of having a multiracial team, with players from all backgrounds and to have achieved many titles with respect. Porto players have never felt the slightest hint of racism and we were very surprised with the accusations."