The Australian - who has made only a handful of appearances for the Stamford Bridge first team - was caught up in allegations that he had tested positive for a Class A drug over the weekend.

It was claimed that Chelsea had only been informed of the positive test at the end of last week and that a B sample has yet to be analysed.

The FA refused to confirm or deny whether a test had been carried out on Bosnich - but if the allegations are proven he faces a lengthy ban.

A statement released by the former Aston Villa and Manchester United player's management company, SEM, read: 'Mark Bosnich has been diagnosed as suffering from severe clinical depression.

'On medical advice, he was admitted to a depression unit of a medical facility to obtain treatment for that depression.

'It would not usually be appropriate to release this type of information, which is private in nature, but it has been decided to do so on this occasion to prevent speculation.

'Mark thanks the press for their support at this difficult time, and asks in the circumstances that further information as to his treatment and whereabouts should remain private.'

Bosnich is reported to have referred the drug test allegations to his lawyers, but a Chelsea statement would only say: 'We cannot comment on the allegations of drug violations made against one of our players.