European Parliament President David Sassoli was hospitalized in Italy since Dec. 26, his office announced on Monday.
Sassoli, an Italian center-left politician, is being treated in the hospital due to a "serious complication" related to his immune system.
His office noted that he had been in a French hospital for pneumonia in September.
"This hospitalisation (in Italy) was necessary because of a serious complication due to a dysfunction of the immune system," his office said in a statement.
Sassoli, 65, has been president of the 705-seat parliament since 2019. His term is going to end this month and he is not expected to seek a second one.
Due to serious illness, he was unable to chair the Strasbourg-based parliament in recent weeks and missed the European Commission's annual state of the union event in September.