Rihanna and Chris Brown spent four hours alone together on her yacht yesterday after he turned up at 4am.
The former couple allegedly locked themselves away in her cabin after spending the previous evening together in the South of France.
A source told The Sun newspaper: "Chris took a car at 4am to Port de Golfe Juan, then a tender to Rihanna's yacht and went straight to her cabin - re-emerging at 8am."
The 24-year-old singer was on his yacht earlier on in the evening, where they moved to a secluded bay.
Earlier, she was seen shopping in Saint-Tropez and Chris' current partner Karrueche Tran was also flown to Cannes, France.
The source added: "Chris Brown's reason for being there is to shoot a video with Swizz Beatz and Ludacris.
"But it just so happens Rihanna is there too, which Karrueche wasn't happy about so she went along.
"There's no way she was missing the trip for him and Rihanna to meet up alone."
Singer Chris is still taking part in a community service programme after assaulting Rihanna in 2009.