National Lottery operator Camelot has claimed that it has lost £1m sales every week since the launch of the Health Lottery in October.

Camelot said cannibalisation among the lotteries would cost the National Lottery’s designated Good Causes and the Exchequer more than £20m a year at current sales rates.

“Since the launch of the Health Lottery in October 2011, we have carried out detailed analysis of its sales impact on the National Lottery,” Camelot said in a statement.

“During this period we believe the National Lottery is losing around £1m a week in sales to the Health Lottery, the majority of which is being felt by National Lottery draws that take place on a Saturday.”

Camelot said the £1m it lost represented a third of weekly Health Lottery sales.

When the Health Lottery launched, its boss, Martin Hall, claimed most of its £250m target for first-year sales would come from incremental growth in the category, with just 11% of players switching from the National Lottery.

Today Hall said he did not recognise Camelot’s figures.

“The Health Lottery has grown the sector,” he argued. “In Q4 of 2011, National Lottery ticket sales actually rose, so it is hard to make the case that they have suffered from our launch. The National Lottery games made £5.8bn in 2011. The Health Lottery target – which we have yet to reach – is 4% of that.”

He added that the Health Lottery had different aims to the National Lottery and was proud to have raised £11m for health charities since October. “We celebrate Camelot’s good works and hope that they will come to celebrate ours,” he said.

Total National Lottery sales during December 2011 amounted to £626.6m, a £57.3m increase year-on-year.  The growth came from EuroMillions sales, up £30.7m on 2010, and instant play games such as scratchcards, up £34.6m.