Algeria's President Abdelaziz Bouteflika is being treated in a French private clinic after being flown into the southern French city of Grenoble on Tuesday, according to local media, reports AllAfrica.
The 77-year-old leader has made few public appearances since being treated for a stroke in France last year.
Bouteflika has been admitted to the cardiology unit of the Alembert clinic in Grenoble, according to the Dauphiné Libéré newspaper, which says that the entire floor has been booked for security reasons.
Over 30 French riot police have been deployed around the hospital and the street has been cordoned off.
Although Algerian officials have not confirmed the news and the exact reason for his hospitalisation has not been mad epublic, a French government source has and French police say Bouteflika flew into Grenoble on Thursday.
A source in Algiers told the Reuters news agency on Saturday that the president would be returning during day after undergoing several tests.
The head of cardiology at the Alembert used to work at Paris's Val de Grâce hospital, where Bouteflika spent 80 days being treated after suffering a "minor stroke" in 2013.
He returned to Paris for minor treatment in January.
Bouteflika has been Algeria's president since 1999 and has not openly indicated a preference for his successor, leading to widespread speculation as to both his state of health and who could replace him.
After returning to Algiers in a wheelchair last July, he was not seen in public for months and his appearances since then have been rare, although he has been seen more often on TV.
On Monday he met French foreign affairs minister Laurent Fabius and economy minister Emmanuel Macron, who were in Algeria for the opening of a Renault car factory.