China is flooding Britain with fake stamps as dishonest companies secure £5 fines for thousands of innocent British victims.

Thousands of fake stamps are entering Britain from China, forcing victims to pay £5 fines to collect their mail.

Royal Mail was urged on Wednesday night to investigate what security experts called “economic warfare”, with Far East counterfeits said to be behind a rise in customer complaints that stamps bought from legitimate sources are being marked as fake.

It is understood that the compelling copies, sold for as little as 4p each, are being snapped up by smaller retailers, who are not required to buy directly from Royal Mail and can instead buy them from wholesalers or online.

Websites seen by China-based Post Office offer sheets of 50 fake stamps at a time, complete with Royal Mail’s new barcode (designed to make mail more secure and efficient) for those willing to commit to a purchase minimum of 20,000.

Last night, Post Office Minister Kevin Hollinrake said he would work with Royal Mail and retailers to investigate. He told the Mail: ‘It is key to prevent counterfeit stamps from entering our supply chain in the UK.

“The Royal Mail must do everything possible to prevent counterfeits from entering our circulation and must establish where they come from and how they enter our market.”

Former Conservative leader Sir Iain Duncan Smith called for a criminal investigation and compared the scam to money printing.

Stamps are considered a “secure printing article” in the same way as banknotes, meaning it is an offense to deliberately reuse or sell used or counterfeit stamps.

He said: ‘The criminal law is very clear on this and I don’t understand why the police are not cracking down. These people are counterfeiters.’

And Alan Mendoza, of the Henry Jackson Society national security think tank, accused China of “stealing revenue from British companies”.

He told the Telegraph: ‘It is inconceivable that a large-scale counterfeiting operation such as this could be occurring without the knowledge and therefore tacit approval of the Chinese Communist Party. It is an obvious form of economic warfare.”

Stamps purchased from the Post Office are not affected because you receive all your stamps directly from Royal Mail’s secure printers in Wolverhampton. They are transported to branches in secure vans or tamper-proof envelopes.

Four major Chinese suppliers are alleged to be printing up to a million fake stamps a week and delivering them to Britain within days.

A large factory only accepts orders for more than 300,000, which reduces the cost to 4p for a counterfeit.

They are then sold through scam websites imitating Royal Mail’s online store and through marketplaces such as Amazon and eBay.

Four major Chinese suppliers are alleged to be printing up to a million fake stamps a week and delivering them to Britain within days. In the photo: Chinese President Xi Jinping.

Both Amazon and eBay insisted last night that they strictly prohibit counterfeit items on their websites.

The news comes after Money Mail raised concerns that customers were being fined £5 for collecting letters that had been sent with barcoded stamps which they said had been purchased from legitimate sources, such as the post office and supermarkets.

Royal Mail said they were fake and the reasons behind this episode are still unclear.

A Royal Mail spokesperson said: “We regularly monitor online marketplaces for suspicious activity, such as deeply discounted stamp sales, and work closely with retailers and law enforcement agencies to identify those producing counterfeit stamps.”