In what is a public blow to Desmond, John Petter, the head of BT's consumer arm, told a briefing at Advertising Week Europe yesterday there was "not a lot to hang your hat on" at Channel 5.
The lack of attractive programming formats, added Petter, did not just rule out the telecoms giant as a potential Channel 5 suitor in the short term, but "it counts us out for any term".
A BT spokesman said the company will not be making any further comment, but it was noted it is also not rejecting Petter's comments.
Desmond's team had hoped that the climate created by the new fierce rivalry between BT, which launched its BT Sport channels in August, and satellite broadcaster BSkyB, might ratchet up the value of Channel 5.
Desmond is believed to be chasing a £700 million deal for Channel 5, the broadcaster he bought three years earlier for £103.5 million.
The deadline for any full and binding bids is 14 April. Media companies still believed to be interested include US giants Discovery and Viacom and possibly BSkyB and UKTV.
If a standout bid is not received, Desmond will consider publicly floating Channel 5.