BBC: French First Lady Valerie Trierweiler has been admitted to hospital after media reports of an alleged affair involving President Francois Hollande.
Her office said she had been admitted “for rest and some tests”.
Mr Hollande’s unmarried partner was admitted on Friday, the day Closer magazine revealed the alleged affair.
Mr Hollande has not denied secretly visiting actress Julie Gayet at a flat near the Elysee Palace but protested at the magazine’s invasion of his privacy.
Ms Trierweiler is expected to leave hospital on Monday, her office told AFP news agency.
On Friday, Closer magazine printed a seven-page article about the alleged affair between Mr Hollande and Ms Gayet.
It was illustrated with photos showing a man said to be the president visiting a flat at the same time as Ms Gayet.
The man said to be the president is wearing a helmet and is ferried to and from the building on a moped.
Mr Hollande threatened to sue over the report, which he called an “attack on the right to privacy”, without denying the allegation.
BBC