A campaign has been launched calling for a ban on the development of robots that can be used for sex.
Such a use of the technology is unnecessary and undesirable, said campaign leader Dr Kathleen Richardson.
Sex dolls already on the market are becoming more sophisticated and some are now hoping to build artificial intelligence into their products.
Those working in the field say that there is a need for such robots.
Dr Richardson, a robot ethicist at De Montfort University in Leicester, wants to raise awareness of the issue and persuade those developing sex robots to rethink how their technology is used.
"Sex robots seem to be a growing focus in the robotics industry and the models that they draw on - how they will look, what roles they would play - are very disturbing indeed," she told the BBC.
She believes that they reinforce traditional stereotypes of women and the view that a relationship need be nothing more than physical.
"We think that the creation of such robots will contribute to detrimental relationships between men and women, adults and children, men and men and women and women," she said.
Abyss Creations, which sells male and female sex toys, is now starting to introduce electronics into its creations.
Meanwhile True Companion boasts that it is developing "the world's first sex robot" and promises to launch its first doll, Roxxxy, later this year.
Chief executive Douglas Hines believes there is a real need for products such as Roxxxy.
"We are not supplanting the wife or trying to replace a girlfriend. This is a solution for people who are between relationships or someone who has lost a spouse.
"People can find happiness and fulfilment other than via human interaction," he added.
He told the BBC that he hopes Roxxxy will eventually become a self-learning engine that is able to talk to her owner and learn his likes or dislikes.
"The physical act of sex will only be a small part of the time you spend with a sex robot - the majority of time will be spent socialising and interacting," he said.
Some experts are sceptical about the claims made for Roxxxy, given the huge complexity of creating intelligent machines but the first version - which will sell for $7,000 (£4,530) - has had thousands of pre-orders, according to Mr Hines.
Dr Kevin Curran, a senior member of the Institute of Electrical and Electronics Engineers, believes such products are about to become mass market.
"We would be naive to ignore market forces for 'intimate robots'. Building human-like robots is quite easy once the mechanics are taken care of," he told the BBC.
"Turning these robots into attractive companions is simply adding a 'skin'. Not difficult at all and not done much to date as most robots are built in research-led institutions - not businesses. That time is coming to an end," he said.
However, he thinks a public backlash is inevitable.
"There have been campaign groups actively voicing opposition to killer robots but I foresee the time soon when humans are lobbying against robot companions or at least shouting 'not in my backyard'," he said.
David Levy, author of the book Love and Sex with Robots, believes that there will be a huge market for dolls such as Roxxy and predicts that by 2050, intimate relationships between robots and humans will be commonplace.
"There is an increasing number of people who find it difficult to form relationships and this will fill a void. It is not demeaning to women any more than vibrators are demeaning," he told the BBC.
As such robots become more sophisticated and are able to simulate human behaviour, so the relationship with humans will become more complex, he thinks.
Dr Curran worries that society as a whole is ill-prepared for an age where sophisticated robotic companions are the norm.
"Have we sufficient legalisation in place for the issues that can arise in a future where robots are sufficiently advanced as to be indistinguishable from humans at first glance? Can a robot marry? Can a robot couple adopt a child?" he said.