The high number of aftershocks from last Monday's earthquake in the Abruzzo region is very ''worrisome,'' Italian Premier Silvio Berlusconi said on Friday.

Since the April 6 quake there have been 806 tremors, nine of which measured between four and five on the Richter scale.

''There has been no let up in seismic activity and this is of great concern,'' Berlusconi said at a press conference following Friday's solemn mass here in the Abruzzo capital for the earthquake victims.