Hartson tweeted: “Ljungberg was a great help to Emery last night.. sat down for 90 mins.. surely you get in the managers ear if you can see what’s going wrong.. Emery had to go.”
Emery oversaw Arsenal’s longest wait for a victory since February 1992, when George Graham was in charge.
The Spaniard’s coaching staff was also dismissed from the club, who claim they have full faith in Ljungberg but are looking for a new permanent manager.
An official statement read: “We announce today that the decision has been taken to part company with our head coach Unai Emery and his coaching team.
A number of Arsenal fans have been calling for Emery’s dismissal for months due to the club’s lack of progress.
The Spanish manager took over after Arsene Wenger’s legendary 22-year reign came to an end last year.
However, the 48-year-old couldn’t take the team forward.