It has been reported that a string of experienced players complained to Allardyce following their heavy defeat to Liverpool on November 24.
Now Harper and Given - the club's longest-serving players - have taken the unusual step of releasing a statement on the club's official website giving their full backing to the former Bolton boss.
The duo said: "Having seen an article in one of this morning's national newspapers, we feel it is vitally important that Newcastle United's two longest-serving players set the record straight.
"The story that has appeared is total and utter nonsense. Sam Allardyce has the full backing and support of every Newcastle United player and we are all working together as one to bring success to the football club."