West Ham chairman Eggert Magnusson has hit out at former West Ham boss Alan Pardew, who he sacked in December.
Pardew took over at Charlton soon after leaving West Ham
Alan Curbishley replaced Pardew - now boss at Charlton - after bad results left West Ham in the relegation zone.
Magnusson told the News of the World: "The key factor was that something was just not right in the dressing room.
"There was no purpose to talk about it publicly at the time. Tension had been building between the players and the manager for a while."
Pardew became Charlton's third manager of the season following Curbishley's departure from The Valley last summer after 15 years in charge.
The pair will come face to face on Saturday as West Ham travel to Charlton, with both sides still desperate for points in the relegation battle.