AOL on Tuesday announced plans to add 400 local sites to its hyperlocal network, Patch, by December.

The web company made the announcement while launching Patch's hundredth site -- Morristown Patch. The network will hire 500 reporters in 20 states, Patch president Warren Webster said.

AOL bought Patch last June for $7m as part of efforts to reinvent itself as a content provider. The network websites are built in communities with 15,000-75,000 residents. Each site is staffed by a full-time editor who works with about 11 local freelancers to create news stories, events listings and classified ads.

Like other AOL websites, such as gadget blog Engadget and video search engine Truveo, Patch sites earn through online ads.