Leicester began the second half at 1-1 after goals from Wes Hoolahan and Richie Wellens but, within 15 minutes of the restart, they were chasing the game as Norwich raced into a decisive 3-1 lead.
Eriksson, whose side are now seven points from the play-offs, said: "It was very bad, I think. The first 45 minutes were good. Both sides played well.
"We all thought at half-time that we could win the game and then it was 3-1 more or less after 15 minutes. We weren't even second to anything. We didn't win any challenge, second ball or anything. We let them have the ball and do what they wanted. I do no know why we started the second half with no energy at all. It was extremely disappointing. I have not seen this team like that before."
Eriksson refused to rule out City's chances of reaching the play-offs despite their return of just one point from a possible 12 which has seen the Foxes slump to 10th place in the npower Championship.
Eriksson said of City's chances: "I don't know, it depends totally on us if we won't go on and have a good season as we were having until four games ago. We have to stand up in the last 10 games."
Source: PA
Source: PA