Transactions at UK’s 12,000 post offices were affected because of a computer glitch on Monday, one of the busiest days of the year in the year.

People reported that long queues started forming in branches after the computer system crashed for the first time.

The Post Office’s network and sales director Kevin Gilliland apologised to consumers for the technical hitch. Gilliland said, "We are very sorry for the inconvenience this problem has caused customers. We know how important the Post Office is to our customers at all times, but especially at Christmas."

The glitch, internally known as Horizon, inconvenienced several people who depend on the network for accessing cash and pensions and benefits, besides mail services.

Two of Royal Mail’s online stamp services have been hit by problems after the company upgraded its computer systems last month.

This is the second time that a computer snag affected operations at the network in six months. Earlier in July, a shutdown blocked access affecting hundreds of thousands customers.