Letters spelling out the demand began arriving at the stations this week.
Officials say gas prices at some stations across the state rose as high as $3.63 a gallon virtually overnight after Katrina hit the Gulf Coast.
Madigan's letter says the stations have until January Fifth to accept the donation offer. It says state law allows her office to negotiate before filing suit in cases of consumer fraud.
Some recipients of the letters say they too were victims of the increases and only raised prices at the same rate as wholesale costs.