The charity chief executives body Acevo has asked nine supermarkets and major retailers to stop selling tickets for the Health Lottery immediately because it gives a lower proportion of its proceeds to good causes than the National Lottery and other lotteries.
In a letter to companies including WH Smith, Asda, Morrisons and Tesco, Sir Stephen Bubb, chief executive of Acevo, says: "There is a very obvious danger that ticket sales for the Health Lottery could detract from sales of the National Lottery and other lotteries.
"Quite simply, this would mean less money going to good causes. At a time when charities are so financially constrained, this would be deeply damaging.
"I would strongly urge you to withdraw your support for the Health Lottery with immediate effect."
Bubb has also written to Richard Desmond, the media owner who launched the Health Lottery. The letter, seen by Third Sector, says adverts for the Health Lottery explicitly compare it to the National Lottery.
"Do you accept that you are consciously trying to lure large numbers of people away from playing the National Lottery and into playing the Health Lottery?" Bubb’s letter to Desmond says. "And do you accept that the inevitable result will be less money going to good causes?"
The letter asks Desmond to confirm whether, as he indicated in a Sunday Times interview in September, he intends to make a profit from the Health Lottery.
The letter also says Acevo is "aware that many of the retailers backing the Health Lottery have moved National Lottery stands to less prominent positions in their stores and put Health Lottery stands in more prominent positions."
In the letter, Bubb asks Desmond: "Did you pay retailers to give the Health Lottery greater prominence than the National Lottery?"
A spokeswoman for the Health Lottery issued a statement that said: "The aim of the Health Lottery is to raise more than £50m of new money for health-related good causes. Importantly, since launch our retail partners tell us there has been no detrimental impact on the National Lottery.
"Some of Acevo’s members have, in their capacity as senior managers of charities, already received grants from the society lotteries taking part in the Health Lottery."
She told Third Sector the Health Lottery had decided not to respond directly in public to Acevo’s allegations. "It seems the best course of action not to add fuel to the fire," she said.
The letter to major retailers names Morrisons as one of the firms that is reported to have moved Health Lottery stands to more prominent positions than National Lottery stands.
A spokesman for Morrisons said: "This is absolutely untrue. We have promoted the Health Lottery, as you would expect, but we haven’t been moving stands."
He said Morrisons did not intend to stop supporting the Health Lottery and that it expected the lottery to "enlarge the market" for good cause lotteries.