Not only was the bid deemed "too low", but the North East club are reportedly reluctant to sell to a direct rival with both teams hovering dangerously above the relegation zone on 23 points.
Brighton are keen to improve their attack this January with only bottom club Swansea City scoring fewer than their 17 goals this season. However, it remains to be seen whether Mitrovic would be the answer to Chris Hughton's prayers as the Serbian has only netted once in the Premier League since the club's promotion in May.
The 23-year-old could blame a lack of first-team opportunities for this goal drought with the striker already expressing his desire to leave Newcastle in an interview with Serbian outlet 'Zurnal' in December.
The Serbian international has made 72 appearances for the 'Magpies', scoring 17 goals, and was part of the club's promotion back to the Premier League last season.