Teesside has been named and shamed as having among the worst postal services in the country - with one in ten letters delivered late.

Just 90.1 per cent of first-class post sent to the area's sorting office reached its destination the following day, according to the National Audit Office (NAO) study.

Only 11 of the 123 mail centres across Britain had a worse performance record in the 12 months to March 2005, the watchdog found.

The figure of 90.1 per cent falls short of the target set for the Royal Mail last year of delivering 92.5 per cent of first-class post the next day.

And the problem of late mail is getting worse, because Teesside does not feature in the list of 20 worst centres for any of the previous three years.

Edward Leigh, Tory chairman of the Commons' public accounts committee (PAC), which works closely with the NAO, accused Royal Mail of "chronic failures at a local level".

He added: "There are still areas in the country - urban areas especially - where it is consistently failing to meet its target for delivering first class post within one working day."

In its report, the NAO blamed the problem on Royal Mail being overburdened with regulation and called for a gradual "withdrawing" by Postcomm, the regulator set up in 2001.

Recommended measures included fewer targets, more automatic penalties and cutting the length and detail of investigations into Royal Mail services.

Ironically, postal deliveries had improved since regulation was introduced, but certain areas - including Teesside, Liverpool, Oxford and large areas of London - were falling short of targets.

Sir John Bourn, head of the NAO, said: "The problem of regulating a monopoly such as Royal Mail is that it tends to involve advocacy, litigation and dispute.

"This report encourages Postcomm to minimise the costs and maximise the benefits in the short term while withdrawing from detailed regulation in the medium term."

A spokesman said: "Royal Mail is currently delivering a record high quality of service to its customers, but we are determined to do even better."

Around 84m items of post are sent every day by businesses and individuals to 27m different addresses, the NAO said.