An elderly man has been arrested for sending threatening letters to high-profile individuals and organisations over 22 years.

Tony Hannibelzs, 71, pleaded guilty just hours after being arrested on Thursday morning for sending 184 threatening and offensive letters since 1994.

Commissioner Andrew Scipione was one of several high-profile people to receive threatening letters from Tony Hannibelsz. Credit:Daniel Munoz

The NSW Terrorism Investigation Squad established a strike force in 2011 to reinvestigate the letters, but a police spokesman said they were not terrorism related.

The 22-year long investigation culminated in a raid on Mr Hannibelzs' home in Koorinda Avenue, Villawood, just after 6am on Thursday.