Birmingham chief executive Xuandong Ren went into a rage and smashed glasses in a private room at St Andrew’s after defeat by Millwall last week.

Sources say the sound of glass breaking could be heard coming from a room which is used exclusively by Birmingham’s directors.

Raised voices, described as a ‘tirade’, were reported after the 2-0 loss, which came three days after Birmingham fan Paul Mitchell assaulted Aston Villa captain Jack Grealish on the pitch. It is believed Ren was responsible for the outbursts.

Birmingham chief executive Xuandong Ren went into a rage after defeat by Millwall last week

The saga of Birmingham breaching Financial Fair Play rules is said to be taking its toll on Ren.

The 37-year-old was in London to discuss his club’s case with lawyers on days either side of the game with Millwall last Wednesday. Birmingham lost to Preston on Saturday to make it four defeats in a row without scoring.

A big points penalty could plunge Garry Monk’s side into trouble as they are 14 points clear of the drop zone in 13th place.

Representatives from the EFL and Birmingham will make their cases to a disciplinary commission this week. Birmingham and Villa were each fined £5,000 on Monday for failing to control their players in the derby at St Andrew’s.