MOORGATE and Liverpool street were placed on lockdown as armed police and sniffer dogs swoop on the area in central London.
Cordons were in place in numerous roads across the city's financial district as armed police investigate.
Police deployed horses and sniffer dogs while Finsbury Circus House office block was evacuated.
City of London police say the evacuation took place due to the discovery of a suspect package in Wilson Street.
A police statement said: "We are currently in attendance at Wilson Street (EC2) following a report of a suspicious package in the area.
"This was first reported to us at 9.52am on Wednesday (20 September) and we are currently investigating.
"We would advise members of the public to avoid the area."
Cordons were put in place at the junctions of Moorgate and South Place, Eldon Street and Blomfield Street, and Wilson Street and South Street.
A Twitter user posted: "Sniffer dogs, guns and our building is on lockdown".