Ten Barcelona players, including Lionel Messi and Xavi Hernandez, underwent "routine" UEFA doping tests on Thursday, just days after a Spanish radio station alleged the club had links to disreputable doctors.
"UEFA doctors paid a surprise visit to Barca's training this morning and carried out routine drug tests on 10 Barca players," the club said in a statement on its website.
"This is the second time Barca have received one of UEFA's routine visits this season, after three last year."
The defending Spanish champions' players last underwent UEFA doping controls less than a month ago.
The latest tests come after Cadena Cope radio on Sunday said Barcelona rival Real Madrid has asked the Spanish football federation to take drug testing in the league "more seriously", saying it does not understand how "doctors with questionable reputations" can work for the Catalan club.
The Catholic radio station, which quoted an unidentified "representative" of Real Madrid, did not name the doctors.
It also alleged that Eufemiano Fuentes, a medical doctor who was one of six people charged in December with trafficking offences in an athletics doping scandal, had worked for Valencia when it won league titles in 2002 and 2004.
Both Barcelona and Valencia have threatened to take legal action against the radio station.
"FC Barcelona wishes to publicly express its total indignation at these unfounded references which link the club to doping practices and to condemn such attitudes, which have nothing to do with fair play and gravely affect the image of sporting competition," the club said in a statement issued Monday.
Cadena Cope has responded with an apology, saying it did not intend to question the honesty of Barcelona and its players but it has not retracted the report.
"We have an anti-doping control today by UEFA, what a coincidence," Barcelona defender Gerard Pique, who was one of the 10 players who were tested, said on his Twitter page.
David Villa, Jeffren Suarez, Jose Manuel Pinto, Andre Iniesta, Victor Valdes, Javier Mascherano and Ibrahim Afellay were the other Barcelona players chosen at random to provide urine samples for analysis.
"This team reflects the values that go beyond football. We have nothing to hide. If we have to undergo 20 more controls, we will do it," Valdes told reporters.
Spain's secretary of state for sport, Jaime Lissavetzky, said Monday he was not aware of any request from Real Madrid to change doping rules.
"Spanish football is clean. We follow every guideline set out by FIFA and UEFA in this regard," he added.
Barcelona's edge over Real at the top of La Liga was cut to five points on Sunday after they were held to a 1-1 draw at Sevilla.
Valencia are in third place, 21 points behind Barcelona.