Authorities are investigating a report that a retired New Jersey locksmith was selling an assortment of New York City "master" keys online.

The New York Post says the keys can unlock construction sites, like the World Trade Center site, as well as subway entrances and some firehouses.

It says they were being sold legally on eBay.

Daniel Ferraris said he got a call from a city fire marshal and stopped selling them as of Sunday.

Ferraris said he'd purchased some from collectors.

The Post said it bought keys from Ferraris for $150.

The keys are distributed to every city firefighter and electrician.

A Bloomberg administration spokesman said it's reviewing procedures involving all-access keys.