"We found an agreement with Newcastle. We gave Loic permission to negotiate with them," Labrune told French radio RMC.
According to media reports, the English Premier League club will pay a 10.5-million-euro (£8.7m) fee for the 26-year-old Remy, who has 17 caps and has scored four goals for France.
Remy, who was in Marseille's squad for their Ligue 1 game at strugglers Sochaux on Sunday, had left his team mates to discuss terms with the Premier League side, a source close to the club said.
The forward is set to join six other Frenchmen at 16th-placed Newcastle, including latest signing Mathieu Debuchy, and will replace Demba Ba at the front after the Senegalese joined Chelsea.
Injury-prone Remy, who joined Marseille in 2010 and scored 27 goals in 60 league appearances in his first two seasons with them, has been struggling to find his form since a thigh injury ruled him out of France's squad for the Euro 2012 finals.
He has started only two league games this term, with coach Elie Baup preferring striker Andre-Pierre Gignac or Ghanain prospect Jordan Ayew up front.
Remy has featured in 164 Ligue 1 games and scored 57 goals since making his debut with Lyon in 2006.