Concerns that changes to the rules which govern the price of stamps could harm small businesses have been expressed by MPs.
The Business Select Committee is currently hearing evidence as part of an inquiry into possible changes to the post office network and the way stamp prices are set.
Under proposals put forward by postal regulator Ofcom, Royal Mail would be free to increase the price of a first class stamp from 46p to a level it deems appropriate and competitive. The price of second class stamps would be capped, but could rise from the current level of 36p to somewhere between 45p and 55p.
According to a report by the BBC, Adam Scorer of watchdog Consumer Focus said businesses that were too small to negotiate their own bulk postal prices should be among the vulnerable customers at the forefront of Ofcom's thoughts when making decisions on prices.
The Scottish National Party's business and enterprise spokesperson Mike Weir MP described the proposals as "damaging", and said the commitment of the UK government to supporting small businesses was "in real question".
He said: "While large businesses that send a lot of mail will never pay the full first class price but benefit from bulk discount from Royal Mail, or have the option of doing a deal with one of the alternative private providers, these options are not available to small businesses.
"Small businesses rely on Royal Mail's service to be able to deliver letters and packages around the country. They could be priced out of the market risking their very survival."