Some councils are "ignoring the findings of road-accident inquests" by switching off street lights to save money, says the AA.
The motoring organisation cited the fact that at least five pedestrians and a cyclist have been killed since 2009 because, according to accident investigators at inquests, drivers had little or no chance of avoiding the collisions on blacked-out roads with speed limits of 40mph or higher.
The AA added that although some councils have recognised the danger and turned their street lights back on, others were "ignoring inquest findings".
In April this year, the AA highlighted official statistics showing that accident reductions between 2007 and 2012 were far less on 40mph roads where street lights had been switched off.
AA president Edmund King said today: "There is growing evidence that cost savings from councils turning off street lights are being paid for with lives.
"In particular, inquests point to a particular danger on roads with speed limits of 40mph or higher."
He went on: "Many of these inquests clear the drivers of blame, which means these tragic deaths are accidents waiting to happen.
"With many more councils switching off their street lights for at least part of the night, the street-light blackout tragedy will just get worse."