Their chests rise and fall and you can hear a tiny heartbeat, but these babies for sale over the Internet are not alive.

"Reborn babies" are disconcertingly life-like baby dolls made of vinyl, which have become swiftly popular with collectors, nostalgic grandparents and grieving parents.

Made by a growing circle of enthusiasts, they are painted several times to create the mottled colour of newborn skin, sport mohair for hair and eyelashes, and are weighted to make them feel as heavy as human babies.

"My daughter wanted a sibling and I didn't want to have any more children, so I made her a doll instead," said Deborah King, who took up doll-making as a hobby three years ago and now sells dolls via Reborn Baby (www.reborn-baby.com).

The term "reborn" refers to the process used to make customised dolls, she said.

Most of King's customers are collectors and grandparents who miss their grandchildren's younger selves, while others just enjoy holding the pretend babies - whose eerily lifelike bodies can be fitted with electronics to mimic heartbeat and breathing.

"People like to cuddle babies. It gives you a motherly feeling," the 32-year-old mother of two told Reuters by telephone.

Contrary to what most people expect, only the occasional customer buys a doll to replace babies they were unable to have, or have lost, King said. She sells the dolls for between 250 pounds to 1,600 pounds and receives 10 to 15 requests a week.

King's Web site features lists of baby dolls photographed in cots and dressed in frocks, some of which are described as "premature". Most have girls' names and are described as "waiting for "adoption".

Other Web sites carry practical tips for people who want to take up the hobby.

Reborn Babies UK (www.rebornbabiesuk.com), for example, includes discussions on a range of doll-making subjects - from processing methods and whether silicon babies are warmer to the touch to how to explain the hobby to friends who find the dolls "too real."

Some members have ordered replicas of their living children.

"The large majority of customers want to collect a work of art. Between 10 and 15 percent are for ladies who have lost a child," said Cathy Newcombe, who runs the Web site.

Counsellors trying to help bereaved parents overcome the loss of a child are increasingly recommending holding the dolls as therapeutic aids, she added.

Reborn Babies' King spends at least five hours a day working on the dolls, which take around seven days to finish from scratch.

"It could be a full-time job if I stopped working tomorrow, but I do need to get out of the house," she said.