An Orthodox priest has been detained over an acid attack that left ten people injured at a disciplinary hearing in an Athens monastery. 

On Wednesday, the 37-year-old priest threw acid at the seven bishops who were discussing removing his licence to officiate, after he was allegedly discovered to be in possession of cocaine in 2018. 

Witnesses say he took a bottle out and started spraying the bishops just as they were announcing the verdict. The seven senior members suffered burns on their faces and hands. 

A police officer who helped detain the subject, a lawyer who was present at the meeting and a clergyman were also injured during the attack. 

Speaking to local media Mega TV, Bishop Artis Kallinikos, one of the victims, said he thought the liquid was holy water. 

"He had the bottle in a bag. When I saw him take out the bottle, my first thought was that it was holy water. My mind did not go elsewhere," Bishop Kallinikos said. 

"I quickly realised, from the sting in my eyes, the liquid was a caustic liquid because it was immediate. Another bishop's face changed colour as soon as the liquid fell on him."

Health Minister Vassilis Kikilias said four out of the seven bishops were lightly injured while the other three needed special eye treatment and plastic surgery. They have all now been discharged from hospital.  

A police spokesperson said the attacker has been moved to a psychiatric hospital and remains under police guard. He was expected to testify during a court hearing on Thursday, a day after the attack, but the judge decided to postpone it as authorities believe he is not in a good state of mind to testify. 

Official charges have not been filed as the police case is yet to be sent to the prosecutor's office.