Winning bond numbers are picked by a machine called Ernie

Savers can buy up to the current limit of �30,000 per person through the new service from National Savings.

Users will be asked to submit their debit card details but credit cards are banned by the Treasury-backed service to prevent irresponsible borrowing.

Bondholders can also check if they have missed out on 400,000 prizes, worth �23m, which have not been claimed.

Investment boom

Investors have piled billions of pounds into Premium Bonds in recent years.

The amount of money saved in the bonds has doubled since January 2000, from �13.8bn to �26bn.

The bonds have been viewed as a safe haven for investors nursing wounds from the stock market woes of 2000 to 2002.

Investment has also jumped since National Savings raised the upper limit on investment from �20,000 to �30,000 in May 2003.

Since September 2004, the odds of winning prizes has shortened from 27,000 to 1 to 24,000 to 1.

However, some believe National Savings should increase prize money further.

One prize of �1m is awarded each month, but 90% of the prizes are either �50 or �100.