We first reported on Renew's recycling bins with integrated display screens back in February, 2012. Though at the time these were spun as benevolent information-imparting godsends, as Gizmag readers noted it was always on the cards that they would be used for advertising – reportedly 95 percent of the time, it turns out. However, in recent days it has emerged that Renew has kitted out 12 of its bins with technology that allows it to detect the smartphones of passers by, and potentially target ads accordingly. Today the City of London asked Renew to stop using the tracking technology.

It was online magazine Quartz that first broke the news that 12 bins on Cheapside in Central London had been fitted with wireless technology developed by Presence Aware which is able to identify individual smartphones of passers by using the unique MAC address that devices use to identify themselves to networks. The technology is capable of identifying which phones, and therefore which owners, pass by regularly, and target ads accordingly – especially if similar devices are to be installed inside retail outlets. A network of such devices would be able to compare notes on an individual's coming and goings. However, the technology does need Wi-Fi connectivity to be activated on a smartphone in order to read it.

The City of London, which awarded Renew with the original contract to install the bins, has today asked the company to desist using Presence Aware's technology.

"We have already asked the firm concerned to stop this data collection immediately and we have also taken the issue to the Information Commissioner's Office," said a City of London spokesperson. "Irrespective of what's technically possible, anything that happens like this on the streets needs to be done carefully, with the backing of an informed public."

Renew Chief Executive Kaveh Memari has said that the company is no longer carrying out field trials of tracking technology, though he has assured the BBC the data is "encrypted, aggregated and anonymised." As part of the original agreement, the City of London is entitled to display public information on the screens 5 percent of the time.

The development is reminiscent of the recently announced OptimEyes billboards with integrated cameras in use in the UK. However, before British readers develop a complex, according to Quartz, Renew hopes to launch the technology in Dubai, Kuala Lumpur and New York, though that was before the City of London's intervention.