IN the UK they are known as kippers, Americans call them the Boomerang Generation, while Japan bluntly refers to them as parasite singles.

Now economists are becoming concerned that stay-at-home adults, who are often well into their 30s, are plundering their parents' savings at such a ravenous rate that there may not be enough left for the retirement years.

New research shows that the 10 million "kids in parents' pockets eroding retirement savings" have in recent years sapped £55bn, or 6%, of the total UK savings market. In the past 12 months alone, adult children received £11bn, or 20% of the cash saved that year.

The trend shows no sign of abating, with many parents resigning themselves to being plundered by the boomer- angers, those who bounce back home after graduation.

Four in 10 ageing parents have dipped into money put by for themselves, in order to help their children out, either as a loan or a gift, and half of these are expecting to have to shell out again.

Some 45% of parents are concerned they will not be able to top up their savings, often used to fund retirement, to a pre-plundered amount, while a third say they would need to make major cuts, often on day-to-day living, to restore their savings.

According to the research, carried out for Scottish Widows and taken from a poll of 2000 people, the average gift is £12,300 and is used in just under a third of instances to get on to the property ladder.

Around a quarter of hand-out recipients use the money for a car, 15% for household furnishings, and 14% for paying off debt. A further 11% need the cash for living expenses, 6% for education fees, and 6% for travelling.

The kippers concept is now so well established that it has even had the Hollywood treatment. Failure To Launch is a comedy starring Matthew McConaughey as the 30-something whose parents attempted a number of plots to remove him from the family home.

Savings experts believe the rising number of pensioners still paying their children's bills will have serious financial repercussions.

Anne Young, of Scottish Widows, said: "Parental responsibility no longer ends when your children reach adulthood but lasts for many years after that.

"Parents may be shocked to learn that their savings could be sapped' by £12,000 after their children leave home."

Professor Merlin Stone, from Bristol Business School, said the drain on the generation heading into retirement could impact on the UK's impending pensions crisis.

He added: "The same generation of children who came home after university before departing to set up their own household are coming back with their hands out for help with the housing, car purchase and even holidays.

"And it looks like this trend is a rising one, for while 39% of those interviewed have given or loaned substantial sums to their children or grandchildren, only 22% of those interviewed has received substantial money gifts or loans from their parents or grandparents."

Professor Stone added: "So the paradox is that while our society is getting richer, it is increasingly dependent on inter-generational gifts. Worryingly, half of these gifts are associated with the investments needed just to get started in life."