Profits at the lottery operator Camelot have also fallen, and last month it laid off 80 staff, including two directors.

Camelot says declining interest in the main Lotto game has been made worse by grants to unpopular causes.

The National Lottery was relaunched in May, with a huge marketing campaign, after three years of declining sales.

It changed the name of the main television draw to Lotto and hired Billy Connolly for a series of TV commercials using the catchphrase: "Don't live a little, live a Lotto".

But sales have continued to fall, down 5.2% in the six months to the end of September - and that means the lottery's good causes have also received less money.

Camelot said people were tired of the main Lotto game - but other games, such as scratchcard, have increased sales.

It claims unpopular grants - highlighted by newspapers - have cost the lottery £500,000 in sales a week.