Darren Ferguson delivered a brutally frank assessment of Peterborough's efforts in a lacklustre FA Cup third round exit to the Canaries.

Ferguson's post-mortem began within an hour of the final whistle at London Road in a behind-closed-doors exchange with his players to sift through the wreckage of a one-sided 3-0 defeat.

'I would never use words like spineless or lack of passion about my players but anyone else who says that having watching them here I can't argue,' he said.

'I don't mind players playing badly or giving the ball away – as long as it's not all the time. They are human beings, I understand that. But I'm not accepting today – no chance.

'You watch Brighton beat Newcastle and there are always shock in this round and we didn't give ourselves a chance. I watched bits of that (before the game). The last thing I said to my players was make it a cup-tie because when you're at home that's what you want to do.

'But when you only have one serious tackle after 65 minutes it is not a cup-tie, it is more like a pre-season game. I've got to ask myself questions and ask the players.

'I'm never one for publicly criticising the players but it was bewildering, the performance today.'

Ferguson's first act in his post-match interview was to offer Peterborough's fans in their biggest crowd of the season at London Road an unreserved apology after failing to exert any concerted pressure on Chris Hughton's much-changed line up for the majority of the tie.

'I have to apologise to our own supporters for that performance because we're at home in a cup game and we've definitely let them down, there's no question,' he said. 'It was a shocking performance. They will expect me to pick them up again either now or Sunday or Monday or Tuesday and perhaps they're starting to take that for granted.

'The most disappointing thing for me was Norwich looked like they wanted it more and they were the ones who made a lot of changes. Norwich, more than anyone, will be surprised by the way we played. You can look at personnel, we didn't have Dwight (Gayle) and we didn't have Lee (Tomlin) but still we have a squad for a reason. I can't put my finger on it but I think everyone who's watched us this season would say it's a really poor performance.'

Ferguson's tongue-in-cheek response when asked for how many reinforcements he would like in the January transfer window to bolster Peterborough's Championship survival push told its own story.

'After this game, 12, if I can. I don't have a number, I never put a number on it. I am as frustrated as I have been for a while now,' he said.

'We tried to get some in this week but we didn't manage to do it. January is a really important month in terms of bringing people in and moving people on. If you ask me now straight after the game I would say I need players in, no question, but I will assess it in more depth.

'I didn't see that performance coming. They're going to have to give me a response, it's as simple as that. It was just such an inept, boring performance. There was nothing in it. Jaanai (Gordon) did well for a 17-year-old and I wish I'd played him now.'

Posh's festive upturn in league form had injected renewed confidence into the ranks, but Ferguson believes they will have to start afresh at Nottingham Forest this weekend after the nature of their cup surrender.

'It's the easiest game Norwich will have all season, without question,' he said. 'All of a sudden, you're back on the back foot. You have a hard game at Forest, then Hull, then I think Bolton.

'It is never a case that you win four out of five and it becomes easier. You have to maintain the same consistency, the same tempo of performance.

'I gave my players two days off and there are no excuses, none whatever. Today wasn't acceptable, the players will know that. I'm not going to single out any players but I think you're entitled to ask for a little but more than we've seen.'