Foster helped Blues win the Carling Cup six months ago but has witnessed the dramatic slump in fortunes since with sadness. City were relegated from the Premier League, saw manager Alex McLeish and more than a dozen players leave and leading share-holder Carson Yeung charged with alleged money-laundering in Hong Kong.
It has left the supporters worried about what lies ahead and Foster believes they need to be put in the picture. And he said: "Am I worried about the future of Birmingham? It is something that a lot of the fans are worried about. They need answers."
He added: "They've been there for the club through thick and thin and the thing that is worrying is that there are not too many answers coming out.
"They (the club) just need to answer things to put the fans minds at ease.
"It is a big shame. I made no secret of how much I enjoyed it last season. Everything was so good at Birmingham. The fans were fantastic and there were some very big highs and very big lows at the end of the season.
"I've got a lot of friends within the club, not just the players but the staff as well, masseurs, physios, people like that. It is not only the players that have to be sold when relegation happens. It is people like that which lose their jobs as well which makes it quite sad as well."
Foster noticed how the effect of relegation had quickly swept through the club when he reported back for pre-season training.
He said: "In pre-season there was something like 12-15 players from last season who had already left. It was a massive change and one thing that comes along with relegation. It was very sad.
"Obviously the debts haven't helped. You see other teams like West Ham and Blackpool go down but they are in a lot more different situation. They have held on to some of their star players. Unfortunately it wasn't possible at Blues."