Czech President Milos Zeman is receiving treatment in an intensive care unit on Sunday, according to his doctor.

Director Miroslav Zavoral of the Central Military Hospital in Prague said Zeman, 77, was admitted due to complications related to an undisclosed chronic condition.

"We know the diagnosis precisely, which allows us to target treatment," Zavoral said, adding that he did not have the president's approval to disclose details of the diagnosis.