Tesco is installing face-scanning technology at its petrol stations to target advertisements to individual customers at the till.

The technology, made by Lord Sugar's digital signage company Amscreen, will use a camera to identify a customer's gender and approximate age.

"It's like something out of Minority Report," said Amscreen's chief executive Simon Sugar, Lord Sugar's eldest son.

A Tesco spokeswoman said: "This is not new technology."

"No data or images are collected or stored and the system does not use eyeball scanners or facial-recognition technology", she added.

The length of someone's hair could be used to work out their gender, she said.

Nick Pickles, from Big Brother Watch, said: "If people were told that every time they walked into a supermarket, or a doctor's surgery or a law firm, that the CCTV camera in the corner is trying to find out who they are, I think that will have a huge impact on what buildings people go into."

Systems could only be "ethically deployed" if customers agreed to opt in to having their behaviour tracked, he added.

You could opt out by wearing a mask, false beard, sunglasses or a hat.

Actually, a better way to opt out is to stop using Tesco. That goes for any other company that brings such a system into play.

I'm not sure walking into a petrol station wearing a mask is to be advised... And besides, that doesn't opt you out, that just means the ads it tries to show you will be poorly targeted.

Tesco is going to want to see some return on its investment. What if it gets bored of generic face data and tries and get more value from the fact that it’s got cameras everywhere? It might decide that it wants to start saving images of every shopper, and matching it to the purchases they make. I'm not suggesting they'd do anything illegal, but consider this: in 2011, an NEC executive let slip that supermarket bosses were showing an interest in cameras that spot their best customers and known shoplifters as they enter a store, and immediately summon a personal shopper and security guard, respectively.

Or it will start advertising baseball bats, solicitors or cheap flights out of the country, one way...

Maybe Tesco would like to have shopper recognition systems in it's shops for all sorts of reasons. But that's not really what this is.

It's called the Tesco club card.

At least that identifies you at the checkout and not before.

No - it identifies the card holder, not the purchaser . All the Tesco vouchers are in my wife's name - but I have a keyring version which I use. So when I buy stuff at Tesco, they aren't associating my purchases with me. I expect Tesco would like to do that, but at the same time allow us to use the same Clubcard account.