NSW Premier Barry O'Farrell has launched a blistering attack on the "bastardry" of a landlord who was seeking to increase rent on his property as the bushfire emergency continued to ravage the state.

Mr O'Farrell said at least one landlord had sought to increase rent on his property in the lower Blue Mountains, where more than 200 homes have been destroyed in the past week during the worst bushfire emergency in NSW in nearly half a century.

Unscrupulous landlords who sought to capitalise on the natural disaster would be named and shamed, Mr O'Farrell said.