A major IT problem affecting Post Office systems has blocked all credit card and debit card payments in branches across the country, as well as locking all 3.3 million Post Office Card customers out of their accounts, it has been confirmed.

The glitch is understood to be on the Post Office's back office systems. Supplier Fujitsu is currently testing a fix for the system, to be released shortly.

This morning, Post Office pin pads, used for credit and debit card payments, have not been working at any of the Post Office's 11,820 branches.

Additionally, customers owning Post Office branded Cards were unable to access their accounts, the BBC reported. Post Office cards are often used by customers to withdraw cash from pension and benefit payments.

The Post Office has offered those locked out of Post Office card accounts with a £20 emergency cash payment, the broadcaster reported, but less than 1,000 people have taken this option.

Cash machines at Post Office branches have not been affected,

Martin Moran, Post Office commercial director, apologised to customers unable to use the pin pads in branches. "We are making every effort to restore these services as soon as possible," he added.