The National Lottery 's website has been hacked and tens of thousands of customer accounts have been accessed.

Organisers Camelot say that around 26,500 online accounts were accessed after the breach happened on Monday, although it has been stressed that no money has been taken from or added to any of the compromised accounts.

Camelot are contacting the affected customers directly. It says that some personal details were changed in about 50 of those accounts, and those customers' accounts are being suspended and re-activated.

For all other accessed accounts, customers are being forced to change their passwords.

In a statement, Camelot said: "We would like to make clear that there has been no unauthorised access to core National Lottery systems or any of our databases, which would affect National Lottery draws or payment of prizes. In addition, no money has been deposited or withdrawn from affected player accounts.

"We are currently taking all the necessary steps to fully understand what has happened, but we believe that the email address and password used on the National Lottery website may have been stolen from another website where affected players use the same details.

"We do not hold full debit card or bank account details in National Lottery players’ online accounts and no money has been taken or deposited. However, we do believe that this attack may have resulted in some of the personal information that the affected players hold in their online account being accessed.

"Cyber criminals such as this are persistent, and we are continuing to monitor and protect our systems. We are also working closely with the National Crime Agency and the National Cyber Security Centre on an ongoing basis on this criminal matter.

"We’d like to reassure our customers that protecting their personal data is of the utmost importance to us. We are very sorry for any inconvenience this may cause to our players and would like to encourage those with any concerns to contact us directly, so we can discuss it with them in more detail."