(Reuters) - Slovak Prime Minister Robert Fico's condition is stable and he is improving, doctors treating him said on Monday, as he recovers from being hit by four bullets in an assassination attempt last week.

Wednesday's attack, the first major assassination attempt on a European political leader for more than 20 years, underscored the deep political divisions in Slovak society.

"After today's medical board meeting, the patient's condition is stable," the hospital in the central Slovak town of Banska Bystrica said in a statement on its Facebook page.

"He is clinically improving, communicating, and his inflammatory markers are gradually decreasing. The Prime Minister remains in our care."

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 the 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.  

One factor suggesting the involvement of other persons was that the suspect's internet communications were deleted two hours after the assassination attempt, but not by the suspect and most likely not by his wife, he said.

(Reporting by Alan Charlish and Jan Lopatka; Editing by Ros Russell)