The club's finances have been in doubt since owner Carson Yeung was arrested and charged with money-laundering in Hong Kong last month.
Yeung is contesting the charges but his assets have been frozen and shares in the club's holding company have been suspended.
Out of his hands: Birmingham keeper Ben Foster could be leaving
Pannu has already watched Barry Ferguson and Kevin Phillips join Blackpool while Craig Gardner was sold to Sunderland for ?5million.
Goalkeeper Ben Foster and defensive duo Scott Dann and Liam Ridgewell could be next and Pannu said: 'Upon my return I may have to make some unpopular decisions and I hope the fans will understand that I effectively don't have a choice.
'The club may need to do what is right and to buy time until Carson's assets are dislodged from the clutches of the courts in Hong Kong.'
Pannu hopes Birmingham International Holdings Limited will be able to meet the demands of its bankers sooner rather than later.
Where to now? Defender Liam Ridgewell could also be leaving St Andrew's
But he was unable to offer any guarantees, adding: 'An update to the fans is long overdue and it is just fair they hear the latest developments from me now.
'But I am not aware of their plans as to how they propose to fulfil the financial distress posed by the relegation scenario and the freezing of Carson's assets in Hong Kong.
'Carson had been trying hard to find new investors but the money laundering charges understandably meant that the progress had been slow.'
Bad for business: Carson Yeung has been charged with money-laundering
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