The "Mean Girls" actress was seen kissing the sister of British music producer Mark Ronson during a party Thursday in Cannes, the Daily Mail reported Friday.
The two women were first romantically linked last year and the media had reported the singer kept in contact with Ronson during her highly publicized stint in a rehabilitation center.
The British newspaper said Lohan also was seen during the party on board a yacht owned by rapped Sean "P Diddy" Combs wearing a ring on her engagement finger.
The newspaper said the appearance of the ring comes as Lohan, who previously has been linked to actors Jude Law and Colin Farrell, is not immersed in any publicized romantic relationships.
Police: Sword-wielding man demanded free tacos
Puzzle-maker slips 'Murdoch Is Evil' into Rupert Murdoch's Sunday Telegraph