In an address to the Police Foundation, Kelly said 673 officers would be stationed at a downtown command post in charge of patrolling the Freedom Tower and the surrounding streets, the New York Post reported Wednesday.
"We are moving forward with the security plan and striving to do so in a way that satisfies the needs of all stakeholders, including the principal need to prevent another attack," Kelly said.
Manpower would be added in stages over a number of years as the complex is finished and occupied, NYPD spokesman Paul Browne said.
The NYPD is actively searching for a location to build the new command center, officials said.
Counter-terrorism Deputy Inspector Donald McHugh has been chosen to head up the command, which will provide security to the entire site known as the World Trade Center complex, officials said.
The complex will include the 9/11 Memorial Plaza, set to open Sept. 11.