Private investment firm Carlisle Capital has made a formal offer to the administrators of Derby to buy the Sky Bet Championship club, the PA news agency understands.

Sources close to the firm say it has made a full asking price offer in the region of £28million.

The bid, which is understood to be spearheaded by the firm’s vice-president Adam Binnie, has been made fully in the knowledge that the club could face additional liabilities if one or both of the claims against Derby from Middlesbrough and Wycombe are successful.

It is understood the offer does not include the club’s Pride Park stadium, which is owned by former Rams chairman Mel Morris.

The group walked away after showing initial interest last year but have returned at a time when the club is facing the very real threat of liquidation, having entered administration last September.

The EFL has asked Derby’s administrators to produce a funding plan by February 1, saying in a statement on Thursday that by the administrators’ own admission, they would run out of cash by the end of the month.

The EFL has also called on the administrators to name a preferred bidder.

The claims of Middlesbrough and Wycombe – and whether they would be classed as football creditors and therefore entitled to the full value of any award arising from their legal cases – have added extra complexity to the situation at Derby, but the bid from Carlisle has been made despite that.