Peter Walton pointed to the spot after Ngog hurdled a challenge from Birmingham's Lee Carsley and went sprawling on the left of the six-yard area.
Both players were booked in an ensuing scuffle before Steven Gerrard stepped up to send goalkeeper Joe Hart the wrong way and force a draw at Anfield that still leaves Liverpool with only one win from their last nine games.
Sinking deep: David Ngog dives into controversy, fooling referee Peter Walton to earn a vital penalty
'I was absolutely nowhere near him,' fumed Carsley.
'It's a joke. I knew that I didn't touch him and I said to the referee to book me or send me off. It would have made me feel better. I'm sure he (Ngog) has a family. Well, if I went home having done that I'd be embarrassed.
Enlarge 'You're supposed to be teaching your kids an example, and that is just an embarrassing case of cheating. But the lad has taken a chance and got his team a point, so I'm sure they'll be patting him on the back.'
Birmingham manager Alex McLeish added to the criticism, saying: 'What happened was a shame for the game. He conned the referee and got his team a penalty.
'Peter Walton is a good referee but he got that one wrong. If it hadn't been for the penalty, I thought we'd have gone on to win it.
'I don't think there is any doubt that Ngog won a point for his side with a clear dive. When it happens, you've just got to take it on the chin. If the referee has another look at it, he will see it was a terrific dive. It wasn't even close to being a penalty, but you always run the risk if you dive into a challenge like Lee did.'
Even Liverpool manager Rafa Benitez, who saw Yossi Benayoun and Albert Riera join a lengthening injury list with hamstring tears, admitted Walton had been taken in by Ngog.
Spot of bother: Stephen Carr protests to ref Walton as Lee Carsley stands bemused by the decision to award dive cheat Ngog a crucial penalty
'I can't say it was a dive, because I haven't seen it properly, but it does seem it shouldn't have been given,' he said.
'I have spoken to David about it and he felt the same way. But so many things have gone against us lately that maybe we were overdue a lucky break. It was disappointing to drop two points after creating so many chances, but I will not talk about the title being beyond us.
'We have won six or seven on the bounce before now and we can do it again.
Late lifeline: Birmingham looked destined for an unlikely victory at Anfield before captain Steven Gerrard rescued Rafa benitez from further woe
'When you look at the spirit the players showed in beating Manchester United, you know anything is possible. They showed it again tonight. They did everything except take the three points.'
Benitez dismissed fears Fernando Torres may need surgery after deciding against including his injured striker.
'He was not confident about playing because of his groin problem, so we decided yesterday that he should concentrate on working with the physio,' said Benitez.
'We are not talking about an operation, just treatment and fitness work.
'Steven Gerrard came through all right and we will have to wait and see now what their chances are for our next game against Manchester City.'
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