In a letter to Jeremy Hunt, the predecessor of the new culture secretary Maria Miller, Sir Stuart Etherington, chief executive of the NCVO, said the Health Lottery could set a "dangerously low" precedent of reducing the acceptable level of lottery funds that must go to charity.
Etherington said that the Health Lottery, which gives 20p in the pound to good causes, should give the same amount to charitable causes as the National Lottery, which donates 28p in the pound.
"NCVO’s view is that a diversity of lotteries may be to the benefit of the sector, creating more diverse funding streams for areas such as overseas aid, cancer or the armed forces," Etherington wrote.
"It is therefore of great importance that the Health Lottery does not set a dangerously low precedent of reducing the acceptable levels of lottery funds that must go to charity.
"One way in which this could be addressed would be to require that the proportion of all lottery funds going to charitable causes to remain in line with the current National Lottery arrangements."
Etherington suggested that a review of the Health Lottery’s impact should be held in October, when it will have been running for more than a year.
In response, a spokesman for the Health Lottery said that a report, commissioned by the National Lottery Commission, the Gambling Commission, and the Department for Culture, Media and Sport, found that the Health Lottery has increased the amount of money raised by lotteries for good causes.
"To date, there is no clear evidence that the Health Lottery has taken very significant revenues from the National Lottery or that it poses a threat to the existing society lotteries," the report said.
"It is likely, therefore, to have increased the total amount of money raised by lotteries for good causes."
Etherington’s letter comes after the High Court rejected the National Lottery operator Camelot’s application for a judicial review of the Gambling Commission's licensing of the Health Lottery.