Ten local government areas hit by flooding in northern NSW have been declared natural disaster areas, allowing relief funds to flow to assist in recovery.

Prime Minister Julia Gillard and NSW Premier Barry O'Farrell made the announcement on Tuesday for the joint funding from the federal and NSW governments.

The declaration triggers a number of disaster assistance schemes to assist with the cost of disaster relief and recovery.

Natural disaster assistance would be available to affected residents, small business owners and primary producers in the Ballina, Bellingen, Byron, Tweed and Nambucca shires, the Clarence Valley, Coffs Harbour City, Kyogle, Lismore City and Richmond Valley.

The NSW State Emergency Service has been inundated with calls for assistance with the heavy rain, strong winds and flash flooding bringing down power lines and trees and ripping roofs off homes.

Further areas could be declared in coming days as the clean-up effort continues.