Egypt's Interior Ministry says investigators believe that "personal reasons" were behind the torture and murder of the Italian student Giulio Regeni, whose body was found in Cairo this month, over a week after he went missing.

The ministry said in a statement on Wednesday that investigation had uncovered no clues to culprits but said "the available information indicates a criminal motive and a desire of revenge for personal reasons."

It warns against "spreading unfounded information" to "mislead public opinion," a clear reference to earlier reports in the international media suggesting the Egyptian police were involved in Regeni's killing.

Regeni disappeared in Cairo on the evening of Jan. 25, when police were out in force to quash any sign of protest to mark the anniversary of the 2011 uprising.