A club spokesman said: "Lee Bowyer has been handed an unprecedented fine, severely censured and additionally warned as to his future conduct by Newcastle United.
"The decision to fine and censure Bowyer was taken after chairman Freddy Shepherd and manager Souness interviewed both players at the club's training ground this morning.
"The fine, amounting to six weeks' wages, is the highest fine handed out by the club."
The club's swift disciplinary action may convince the Football Association and the police not to launch separate investigations into the incident.
Shepherd said: "No one is more embarrassed than me. It was a black day for Newcastle and, speaking personally, the worst day I have experienced as chairman of this football club. I never thought I would see two of our own players fighting."
Unless the FA overturn Dyer's suspension, both players are set to miss Newcastle's FA Cup semifinal against Manchester United as well as Sunday's Premiership clash with Spurs.
Earlier today, Caborn had urged Newcastle's directors to make an example of the pair. He said: "It is not just the 50,000 fans who were there, it is all the young people who see that type of behaviour on a pitch with professional players. That's replicated in the playground."
Meanwhile, it emerged today that Sir Bobby Robson received a £2.1million pay-off from Newcastle following his sacking last September.
The pay-off formed part of the club's interim accounts which recorded a rise in profits for the six months to the end of January. They announced a retained profit of just over £5m, up from £635,000 last year.
