A single postal service at a later time is being trialed in 14 areas across the country, Consignia announced on Tuesday.

The move is an attempt to reduce company costs and to improve the efficiency of the service.

"Royal Mail has to deliver a reliable universal service to everyone for the price of a stamp, including to many places where the cost of that service is considerably more than 27p," a spokesman said.

"The regulator is increasing the pressure on Royal Mail with the proposal to open the most profitable elements of the market to competition in just a few weeks time. Our delivery patterns have not changed for many years and we believe there is scope to increase efficiency and improve reliability."

Trials will be held in areas including Plymouth, Crawley in Sussex, Loughborough and Edinburgh.

Reacting to the news, the postal services watchdog Postwatch called for customers to have their say.

"Postwatch cannot support changes to delivery service without a full understanding of customers views and experiences. In order to represent customers properly, we must find out what they want, how they perceive the changes, and the impact they have in practice. That is why we have insisted on effective, independent customer research as part of the trials," said chairman Peter Carr.

"If Consignia wants to be customer focused, it will also want to know what customers think about proposed changes before pushing ahead. There will have to be sufficient time to evaluate the results of the research. Consignia will also we expect want to consider some degree of local flexibility. It is not necessarily a case of one size fits all."