Reports in Portugal quote the player's agent, who alleges that the teenage winger was the centre of a attempted kidnapping last night by a group of Sporting Lisbon supporters.
Bruma is now resolved to leaving the Portuguese club, with a huge number of Europe's top teams sure to be interested.
Manchester United and Porto have been linked, while Chelsea are thought to have had a €2m offer rejected. Turkish giants Galatasaray have also made a bid, claims Bruma's agent Catio Balde.
Balde told Portugese radio station Antena 1: "We have pressed charges. This is a very serious and unpleasant matter, and it led to this decision."
The kidnapping plot is believed to be in response to reports that Bruma begged Sporting to let him leave the club for Chelsea.
The report now claims Bruma is determined to cancel his contract with Sporting in light of the attempted kidnapping, but the case will be sent to FIFA for adjudication. An outcome could be months away.
Balde continued: "I was in charge of presenting offers to Sporting. There are offers from foreign clubs, from Chelsea and Galatasaray, worth €8m that could reach €12m.
"From this moment on, considering that he is a highly-coveted player, it is possible that more offers will arrive, because I know that several clubs were waiting for the best moment to make a move."
When pressed on whether Bruma would look to leave the club as soon as possible, Balde said: "Right now, Bruma's mind is not on Sporting."
The 18-year-old winger has starred at the Under-20 World Cup in Turkey for Portugal, after breaking into the Sporting first-team last season.
His performances, and the club he plays for, have led to comparisons with former-Sporting youth team star Cristiano Ronaldo.