UK officials are considering banning the sale of small mobile phones designed to resemble car key fobs.
A government spokesman told the BBC that it was discussing the issue with the National Trading Standards Board and the Serious Organised Crime Agency.
In the meantime the NTSB has asked retailers to stop selling the products.
The Times had reported some of the Chinese-made products were being advertised with prisoners in mind - having a mobile in jail is an offence.
The devices, in some cases marketed as the "world's smallest mobiles", are available from mainstream retail websites including eBay and Amazon.
They are designed to resemble the fobs used to transmit a signal to unlock vehicle doors, and feature logos from brands including BMW, Volkswagen, Bentley, Audi and Porsche.
A spokesman for the UK's Society of Motor Manufacturers and Traders said it believed the devices were being made without its members' permission.
The product description of one device sold via Amazon states that it features "very very very low metal contact badges [which] can be removed due to metal content alarm", while another says the fob is "easily concealable".
The Times said it had spotted one advertised elsewhere alongside a cartoon of a prisoner behind bars.
A prison service spokesman said it was already making efforts to detect the devices.
"A range of techniques - including body orifice security scanners and high-sensitivity metal detectors - has seen the [overall] number of recorded seizures increase," he said.
"We're now working closely with the Serious Organised Crime Agency and Trading Standards to remove these small mobiles from sale in the UK, as well as legislating to block phone signals in prisons."
More than 7,000 phones and Sim cards were confiscated in prisons in England and Wales last year.
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Wow, these mobile phones are tiny.
