A Barcelona court agreed to take on the case last week after prosecutors filed a complaint over what they alleged were payments of 7.3 million euros from 2001 to 2018 to firms owned by Jose Maria Enriquez Negreira.
Negreira was vice-president of the refereeing committee of the Spanish Football Association from 1993 to 2018 under then-president Victoriano Sanchez Arminio.
Negreira was not immediately available to comment.
UEFA said in a statement on Thursday: "In accordance with Article 31(4) of the UEFA Disciplinary Regulations, UEFA Ethics and Disciplinary Inspectors have today been appointed to conduct an investigation regarding a potential violation of UEFA’s legal framework by FC Barcelona in connection with the so-called 'Caso Negreira'."
State Attorney General Alvaro Garcia Ortiz on Tuesday asked for the case to be transferred to the anti-corruption prosecutor's office due to the high-profile nature of the allegations.
The prosecutors' complaint focuses on 2.9 million euros paid from 2014 to 2018 and alleges Barcelona, with the help of the club's former presidents Sandro Rosell and Josep Maria Bartomeu, reached a "confidential verbal agreement" with Negreira.
In a statement last month the club denied any wrongdoing, saying it had paid an external consultant who supplied it with "technical reports related to professional refereeing". It was a common practice among professional football clubs, it said.
A senior Barcelona official told Reuters the club had expected the prosecutors' complaint and described it as "nothing more than an absolutely preliminary investigative hypothesis".
The official said the club would fully cooperate with the investigation and it reiterated that "they have never bought any referee nor have tried to influence any official's decisions".
"I am looking forward to confronting all the scoundrels who are tarnishing our shield," Barcelona president Joan Laporta told an event held by the club with the captains of the different Barcelona teams earlier this month.
Rosell was not immediately available to comment.
LaLiga said earlier this month that it had reported the case to UEFA because no punishment could be handed down under Spanish sports law since three years had passed since the alleged infringements, according to its president Javier Tebas.
"As we could not intervene because it was time-barred, we wrote to UEFA who can do so at the international level," Tebas said in an official statement earlier this month.
