Bielsa in scuffle with stadium contractor

The Argentine coach told a more than hour-long news conference he lost his cool after returning to the club's Lezama training facilities, which looked more like a construction site than a football field for pre-season training.

"I was furious that they wouldn't recognise the problems and I started verbally abusing them. I then took him by his body and threw him out," Bielsa said.

"He's got the right to report me to the police, I've already turned myself into them. But he did not file any complaint to the police because he was probably pressured not to by his bosses or by Athletic."

Surprisingly, Bilbao refuted Bielsa's claims on Friday, apologising to the construction company for any damage to its image caused by Bielsa's comments. The Basque team said work was on schedule.

Bielsa, whose nickname is 'El Loco' (The Crazy One), said his frustrations over the situation boiled over when he returned from summer holidays to find the outdated facilities in a poor state.

"You can't have a squad worth 300 million euros and not proper playing fields," said Bielsa, who is heading into his second season in charge.

"To start the season in conditions such as these makes a mockery of me as a coach because I am the one responsible for the working conditions being this way."

Bielsa led Bilbao last season to the Copa del Rey final and to its first continental final in 35 years by guiding it to the Europa League final.