Westfield Sydney - packed with food, fashion and tourist businesses - has closed and evacuated staff and thousands of lunch-hour shoppers following a power outage in the CBD on Thursday morning.

The Sydney Tower Eye at the top of Centrepoint Tower has closed for the day because of the outage.

Westfield spin-off Scentre Group is negotiating to sell $1billion worth of its malls. Credit:Bloomberg

The offices of the Australian Securities and Investments Commission has also reportedly been evacuated.

Power has been partially restored to the 1100 homes and businesses between Goulbourn and Market streets.