SEX robot customers are asking for some very kinky "extras" to be added to their silicon love machines, it has emerged.

Porn star Harriet Sugarcookie revealed that she visited a factory run by the sex robot firm RealDoll and discovered the naughty dolls can fulfil any fantasy.

She said they could be fitted with three breasts, elf ears or even a cat tail.

The bizarre customisations are reminiscent of the Arnie film Total Recall, which featured a three-breasted prostitute.

"There's so much craftsmanship that goes into the work! I saw a workstation where they were making dildos," she told The Daily Star.

"And this guy has the job of carving out the details, like the veins on the shaft of the penis and the wrinkles on the balls."

Robot sex dolls are becoming big business and manufacturers are now claiming their products are so realistic people are marrying them.

Foundation for Responsible Robotics chairman, Professor Noel Sharkey, said guilt-free threesomes was just one of the potential uses for sex robots.

Others include "teledildonics" - wireless technology which allows a person to stimulate their partner remotely.

Sex bots are becoming hyper-realistic, with features such as built-in heaters to create the feeling of body warmth.

They will also have sensors to react to your touch.

One company is even developing a head that can speak, smile and sing for its robot sex dolls.

Meanwhile, sex bot Harmony, which is created by RealDoll, is the first to offer an "emotional connection".

Experts say these specialised robots will start to appear in ordinary homes in the next decade, as lonely humans look for love.

Futurologist Dr Ian Pearson believes women will be ditching men for robots when they want to get frisky in 10 years' time - and could ever start falling in love with the machines.

In fact, he reckons by 2050 robot sex will have eclipsed human lovemaking altogether.

David Levy, author of Love And Sex With Robots, said: "I've no doubt some will find it creepy, but the arrival of sexually responsive robots will have enormous consequences.

"We have already seen rapid changes in human relationships thanks to the internet, mobile devices and social media.

"The next major advance will enable us to use our technology to have intimate encounters with the technology itself - to fall in love with the technology, to have sex with robots and to marry them."

This article originally appeared in The Sun and has been republished here with permission.