Smartphones stolen during the recent riots in London and other cities appear to be turning up for sale in large numbers, goods tracking company Recipero has found.

In the last week the company said that the number of stolen items being reported into its CheckMEND database, used by mobile networks and the police to check for stolen goods, had gone from 2,000 to 6,000 per day and rising, an unprecedented spike.

To be clear, these handsets are those detected as having been stolen, which offers some insight into the scale of the theft that occurred during the riots. Some of these extra handsets were being entered by police forces after raids on those suspected of handling stolen goods, but others were being discovered after being offered for sale to phone recycling companies, cash converting businesses and the second hand trade.

Recipero estimates the number of phones stolen during the disturbances may be "somewhere in the tens of thousands", with 430 smartphones reported stolen from one store alone. An unconfirmed report emerged in recent days of a suspicious batch of 40 smartphones being sold through a prominent online auction site.

Members of the public should check any smartphone they are considering purchasing for £1.99 per item by entering the IMEI or serial numbers into CheckMEND, said Recipero managing director, Adrian Portlock.

"An iPhone 4 is the lowest depreciating device on the market," said Portlock, who said that even a one year old iPhone would still fetch hundreds of pounds second hand. This made Apple devices especially valuable with other high end smartphones close behind.

Sites such as eBay were now recommending that consumers check IMEI numbers for sale goods using CheckMEND.

"As a force we are determined to track down as many stolen items of property as possible and we don’t want members of the public purchasing them from looters," said the West Midlands Police Mobile Phone Crime Unit, which reports stolen device finds into a central database run by the police National Mobile Phone Crime Unit. "We have therefore loaded as many of the serial and IMEI numbers of the stolen goods to the Recipero databases both so we can identify the stolen property but also to help the public avoid them by using CheckMEND."

Buying a stolen device in the UK will be futile. Once processed as a stolen handset, the device will be deactivated and unable to connect to any UK network. The assumption is that many deactivated smartphones will then be sent abroad for reprogramming and connection to foreign GSM networks.