The Royal Mail has admitted that half a million items of post go missing each week.

Most problems occur when mail is delivered to the wrong house by mistake, but poor addressing was also cited as a cause.

The company has vowed to introduce more measures to stop items going astray, but it is also facing criticism by the industry regulator for failing to achieve its delivery targets.

15 million badly-addressed letters still reach their destination

Mick Linsell, managing director for Royal Mail's service delivery division, said action to improve delivery would include better equipment at sorting offices to cope with increased volume of mail and better training for new recruits and temporary employees.

But he added: "All the research and analysis we have done shows that the amount of correctly addressed mail which does not reach the right person is very small, less than 0.1% of our overall volume of 82 million letters a day.

"Every letter is important to Royal Mail and we are taking action to cut the amount of mail which is mis-delivered, for whatever reason."

The target for first class deliveries is that 92.1% should reach the destination the next day. A total of 91.6% are currently meeting that deadline.

Our people accomplish some real feats in delivering badly-addressed mail on time.

Mick Linsell, MD Royal Mail service delivery division

The research was undertaken as part of the licence which Royal Mail was granted by the industry regulator Postcomm.

The licence requires the company to ensure stringent mail protection measures and to provide annual estimates of lost post to Postcomm and to the consumer watchdog Postwatch.

Mr Linsell pointed out that more than 15m badly addressed letters still arrived at the right place and on time each week.

Illegible

"Our people accomplish some real feats in delivering badly addressed mail on time.

"Some have directions instead of addresses and even descriptions of the intended recipient."

Some 72m illegible or indecipherable letters which have no return address are sent to the National Return Letter Centre in Belfast, which manages to return a quarter of them successfully usually within 14 days, he added.

The news comes just a month after the then named Consignia (now Royal Mail Group) announced an experimental plan to charge households and small businesses to receive letters early in the day.

The idea was to charge businesses and individuals �14 a week for having fewer than 20 letters delivered before 9am in order to make the service more efficient.

However, plans are afoot for a re-think after widespread criticism.