By Duncan Mackay

London 2012 has contacted all 1.8 million people who have applied for tickets for next year's Olympics to remind them that they need to make sure that they have enough money available in their accounts to cover the cost of what they ordered or risk losing them.

An estimated 20 million London 2012 Olympics tickets had been applied for by the time the process officially closed last week, and the signs are that many people have booked more tickets than they can afford.

With the average ticket application exceeding 10 per person and an average ticket price of between £50 ($83) and £200 ($330), applicants are set to receive bills of hundreds or even thousands of pounds in the next few weeks.

People had to select tickets through the online bidding system and pay for them on a Visa card but were not told at the time whether their applications were successful, so many have potentially committed thousands of pounds to make sure they get tickets to something.

But if they do not have enough money to cover the cost then they face the propsect of losing them.

"This is a reminder email from the London 2012 Ticketing team," said the e-mail.

"Please ensure you have sufficient funds available on your Visa card to cover the total cost of your application between 10 May and 10 June 2011.

"Please be aware that your application may be withdrawn if you do not have sufficient funds available.

"The latest date by which you will be told whether you have been allocated tickets is 24 June 2011."

Those who have acquired tickets to events they might not be able to attend, or have bought more than they can afford, will be able to sell back tickets through an official re-selling platform but that will not be available until early next year.