The Championship club has stated that it is in talks with the Premier League side about the possibility of the English keeper moving to Anfield in the January transfer window
The highly-rated keeper is being touted by the Merseyside club as a replacement for Pepe Reina, as Goal.com exclusively revealed earlier this month.
With the Championship side struggling financially since their relegation from the Premier League, they may be forced to sell some of their most prized assets in order to keep afloat.
And acting chairman at St. Andrews, Pannu, has confirmed that Liverpool is interested in the young goalkeeper, however the Reds aren't the only club that is keen on the England international.
He told the Birmingham Mail: "I understand there are talks with Liverpool, I understand that Everton might be interested, Southampton gave me an offer in the past, I know not whether they want him.
He added, "What I can say is that - and I might be blasted for this by the fans - but no one is for sale and everyone is available. As in any club.
"Give me a £15 million offer for Jack Butland, can I say no?
"I have rejected £6m from Southampton [in the summer] but I rejected it when our finances were OK.
"As the time is ticking, I might not be able to reject it if I get something similar."