Troubled Lottery operator Camelot is to look again at the £15 billion it has promised to good causes over its next seven-year licence period.

It comes after chairman of the Lottery Commission, Lord Burns, estimated it would fall short of the pledge by about £5bn.

The regulator said Camelot should give "at least" £10bn to good causes during the second licence period.

Camelot is expected to miss its targets because of falling ticket sales and competition from other types of gambling, which the Government plans to deregulate.

Annual lottery ticket sales fell below £5bn last year for the first time in four years, the company announced in May.

Camelot and Sir Richard Branson's People's Lottery, which challenged it for the licence last year, both pledged to raise £15bn for good causes over the seven-year licence span.