The south coast club are desperate to sell the hitman to the Clarets for £3.5m to help pay off their debts.
Going nowhere: Nugent
A deal has already been agreed between the two clubs but Nugent would rather stay on loan for the rest of the season instead.
He is due back to Fratton Park on Tuesday if Burnley are unable to agree a loan switch but is keen to remain with the Clarets.
Burnley boss Brian Laws said: 'He wants to stay here for the rest of the season. He wants to leave everything about his future until the end of the season and concentrate on playing.
'We are trying to talk to Portsmouth to sort out some kind of deal but that is taking it's time at the moment.'
Portsmouth's cash nightmare hit a new low on Wednesday when Sol Campbell sued his old club for £1.7m of unpaid image rights and bonus.
They have also seen £10m of TV money withheld by the Premier League and are struggling to lift a transfer embargo.
Nugent signed for Pompey in a £6m in 2007 but failed to make his mark at Fratton Park.
Tottenham, Manchester City and Sunderland in £10m race for Portsmouth defender Younes KaboulStoke set to revive James deal as Portsmouth re-open talks over keeperPORTSMOUTH FC