The postal service has endured a shake-up to cut costs

Only three out of 16 performance targets set for the year ending in March were met - half as many as in the previous year.

Royal Mail says its overall performance has improved and its first class service is the best it has been for seven years.

But the postal services regulator Postcomm, which sets the targets, told BBC News Online it would consider fining the company.

Results 'misleading'

As well as failing to meet the minimum performance targets for the delivery of first and second class post, Royal Mail also failed to meet targets for its special delivery service.

But the average performance of first class mail was 2% higher than in the previous year.

A Royal Mail spokeswoman said the results, which are taken from two months of the year, were "misleading" and that the service was improving.

"We're not saying we've done brilliantly but some of the targets were missed very narrowly," she said.

These are very disappointing results coming at a time when customers are paying higher prices for their post Peter Carr Postwatch

"The cumulative results for the whole year do demonstrate an improvement."

Postwatch, the postal services watchdog, said the results meant that more than one million first class letters a day did not arrive on time.

Chairman Peter Carr said: "Furthermore, whilst no individual postcode area should achieve less than 90%, nearly one in 10 failed even this minimum standard.

"These are very disappointing results coming at a time when customers are paying higher prices for their post.

"These targets are minimum standards and although some progress has been made, this has been a year with virtually no strikes or severe weather conditions to hamper delivery."

Losses halved

A spokesman for regulator Postcomm told BBC News Online: "We're extremely disappointed Royal Mail has failed 13 of its 16 targets, including two already under enforcement action.

"We will consider seriously how to respond, including looking at the possibility of imposing financial penalties."

The licence issued by Postcomm sets a year-end target for the months of February and March.

The most reliable mail is in Sunderland

Performance was 91.7% against a target of 92.5%, a margin which disappointed Royal Mail's UK managing director, Jerry Cope.

He admitted there was still "much to do", although the company had become more stable as a business.

Royal Mail is one year into a three-year renewal programme designed to turn the company around.

Last week, Royal Mail said it had cut its annual losses to �611m after its first improvement in trading performance for five years.

Mr Cope added: "We are determined to do better for our customers and meet the licence targets in the current year."

The best performing postcode area for next-day delivery was Sunderland.

South-west London was rated the worst, which came as no surprise to residents there.

Brian Massey, who lives in Barnes, told BBC News Online: "The post here is very erratic. Some first class letters take a day, some take a week and some don't arrive at all."