From today, a first class stamp costs 39p for standard letters that weigh up to 100g, while a second class stamp is now 30p for a letter of equal weight.

Royal Mail has also increased the price of stamps for large letters – 61p for first and 47p for second – hikes of 9p and 5p respectively.

Richard Higginbotham, marketing manager at CDMS, said any increase in mailing cost is going to have a big impact.

"Usually the cost of mailing the item is the largest in a campaign. Now more than ever, companies need to increase the targeted, focused nature of their mailings," he added.

Sending a packet up to 100g first class now costs £1.28, while a second class packet costs £1.08.

Royal Mail has said that all increases have been made within the parameters set by Postcomm.    
The mail operator has also raised the price of its Special Delivery service, increasing it by 35p to £4.95 for standard packets up to 100g.

David Bland, chairman of ViaPost, which allows customers to send physical letters from their desktop, said the price increases showed "how little the Royal Mail understands its customers".

He said: "While already operating in a very tough economic environment, this price rise will cost UK businesses approximately £50 more per 1000 letters they send.

"Last year, the Royal Mail handled over 20bn letters in the UK, with 87% of them being business-related mail. Therefore, these increases in costs are going to have the biggest impact on UK businesses."

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