Athletic Bilbao say they did not give midfielder Javi Martinez permission to travel to Germany on Tuesday amid speculation the Spain international has already taken a physical with Bayern Munich.
Martinez, 23, has been closely linked with a big-money move to the Bundesliga giants and looked a step closer to sealing a switch to the Allianz Arena after being spotted in Munich on Tuesday.
Bayern president Uli Hoeness told Bayrischer Rundfunk he was "very optimistic" that the transfer could be completed within the next few days.
However, Athletic said Wednesday that they didn't authorize Martinez's trip to Germany.
"Athletic wishes to make clear that at no time did they authorize the trip of their player Javier Martinez to Munich on Aug. 28," Athletic said in a statement.
Athletic said they have also asked the World Cup winner for an explanation.
Information from Press Association was used in this report.