Drastic action is being considered in the battle to get more men to step forward and save the nation

Couples are to be offered free fertility treatment in return for donating sperm to other women who are desperate for children. The offer, by the Care group of IVF clinics, comes as fertility experts warned that the shortage of sperm stocks in the UK was reaching crisis levels and had plummeted to a record low.

The chronic shortage of sperm stocks in the UK has also prompted approaches to Britain's soldiers to donate sperm, in a move reminiscent of Lord Kitchener's "Your Country Needs You" recruitment campaign in the First World War.

Several families with men in Iraq and Afghanistan are having sperm frozen in case they are killed or rendered infertile as a result of the conflict. Sperm can be used after a man's death if he has given legal consent.

Now army recruits are being approached about donating sperm. In addition to a national recruitment drive being discussed by fertility clinics, families of servicemen will be able to freeze sperm for free for their own personal use in return for donations to the sperm bank run by Fertility4Life.

New proposals are also being framed to recruit semen donors at military bases to address the serious sperm shortage. The samples could be distributed to sperm banks around the UK.

A working group of fertility experts is drawing up proposals for a national recruitment campaign that will target groups such as the police and firemen, as well as the military, as potential donors.

The National Gamete Donation Trust, a government-funded body that helps recruit donors, said it was looking at targeting places where "men congregate", including rugby matches and army bases.

The Department of Health has also recently received a proposal from Fertility4Life, the biggest online sperm bank, to launch a recruitment drive among the military.

John Gonzalez, Fertility 4Life's chief executive, said: "We have had people inquire about freezing squaddies' sperm and we are looking at the possibility of taking extra stock to help with the diminishing stock of sperm."

The move comes as Britain's biggest chain of private fertility clinics plans to offer a free cycle of IVF treatment worth £2,500 to couples if the man agrees to become a sperm donor.

Fertility clinics have been forced to order emergency supplies from the US and Spain after the number of donors dropped dramatically following the Governments' decision to change the law on anonymity to allow children to contact their donor fathers. Children born to sperm donors at UK fertility clinics now have the right to seek out their biological fathers when they reach the age of 18.

Figures from the Human Fertilisation and Embryology Authority show that only 12 new volunteers register each month to become donors. Before the anonymity of donors was abolished, the figure was 19 a month.

The Care fertility clinic chain, which has sites in Nottingham, Manchester, Sheffield and Northampton and in hospitals around Britain, is planning to offer a "sperm sharing" scheme in the UK. This would allow men whose partner is undergoing IVF treatment to qualify for a free cycle if they agree to donate sperm to other women seeking fertility treatment.

In many cases of couples seeking IVF, the man has no fertility problem and has tested positively for healthy sperm.

The scheme will be welcomed by couples who cannot afford the full cost of private IVF treatment as well as women who are being denied children because they cannot find a suitable donor.

However, it is likely to prove controversial in some medical circles. Experts are expected to warn that men who have failed to conceive with their wife or partner could be traced by children born from donated sperm many years later, which could cause them serious trauma.

Information packs for men up to the age of 45 are currently being prepared. These will include details of the free fertility treatment if they agree to make regular donations of sperm that can be frozen and stored for use for other couples to use.

"This is something we are planning to resolve the very serious shortage of sperm," a Care spokeswoman said.

The clinics have already begun an egg-sharing scheme offering IVF treatment for £500 in return for donating eggs. There is currently a huge waiting list of single women, couples where the man is infertile and lesbian couples who want children because of the donor shortage.

Some have even been told they could face a five-year wait for a donor to come forward who has sperm that matches their physical requirements.

A recent survey showed that more than two-thirds of clinics have either no sperm stocks or are having "great difficulties" in obtaining them.

The shortage has led some fertility clinics to close their sperm banks and in some areas of the country there are no sperm supplies at all. There is now only one donor in Scotland.

Almost 70 per cent of clinics in the UK say they are currently receiving "no sperm" or are having "great difficulties' finding it after the Government changed the law last year to remove donors' anonymity.

The quality of sperm being donated is also falling, so for every 100 men who enquire about donating only five will have sperm that is healthy enough to use.