"At the same time, further actions are being taken to improve his health condition," the hospital in the central Slovak town of Banska Bystrica said in a statement.
Wednesday's attack, the first major assassination attempt on a European political leader for more than 20 years, underscored deep political divisions in Slovak society.
Deputy Prime Minister Robert Kalinak said on Sunday that Fico's life was no longer in immediate danger, although his condition was still too serious for him to be moved to a hospital in the capital Bratislava.
Meanwhile, Interior Minister Matus Sutaj Estok said on Sunday an investigation team had been set up, which would look into whether the suspect had acted alone as initially believed.
The 71-year-old suspect, identified by prosecutors as Juraj C., is a former shopping mall security guard and author of three collections of poetry.
Investigators will seek to determine whether he was part of a group of people who had encouraged one another to carry out an assassination, Estok said.
