In its latest revelations about a saga that has made headlines around the world, Closer magazine said Hollande had been introduced to Julie Gayet, 41, during campaigning, fell for her immediately and "relations quickly became more intimate."
The latest edition of the glossy weekly hit stands as Hollande's office confirmed that he had visited his official partner, Valerie Trierweiler, for the first time since she was hospitalised in the wake of the affair revelations.
His failure to visit earlier had helped to fuel speculation that he has decided to end the relationship with Trierweiler, for whom he left Segolene Royal, the mother of his four children, in 2005.
Hollande has said he will clarify the position of France's de facto First Lady before a trip to Washington next month but has refused any other comment on the scandal.
Also Read
Closer, which is being sued by Gayet for alleged breach of privacy, reported last week that she had been having secret trysts with the president and published photographs of the pair arriving separately at a borrowed flat near his official residence, the Elysee Palace.
In its follow-up story, Closer depicted Hollande's romance with Gayet as much more than a brief fling, although it offered little in the way of concrete evidence and, unlike last week's scoop, no pictures to back up its account.
The magazine said the couple had also regularly met at another Paris apartment and at Gayet's loft in eastern Paris, where she hosted frequent dinner parties for members of France's artistic, intellectual and political elite.