Dr Mark Hamilton and Dr Allan Pacey, of the British Fertility Society (BFS), said the UK was struggling with a serious shortage of sperm donors.
Writing in the British Medical Journal, they said radical reform of the current system was needed.
They blamed removal of donor anonymity in 2005 for the donor shortage. Children can now trace their biological parents when they are 18.
Overall, the number of sperm donors has fallen by 40% in 15 years.
The experts warned that many fertility clinics have long waiting lists, or have been forced to stop providing services altogether.
At present around 4,000 UK patients request donor sperm each year.
Under UK law, the maximum number of pregnancies that can be created from a single donor is 10. This is to reduce the risk that children born from sperm donated by the same man will have children together in later life.
Therefore, assuming not all donors would consent to their sperm being used in 10 pregnancies, a minimum of 500 new donors are needed every year to meet demand. But in 2006 there were only 307 new registrations.
Dr Hamilton and Dr Pacey argue that the current limit is arbitrary and not evidence based – and a more flexible approach is needed.
They point out that the size of the UK population is enough for a large safety margin to already exist.
In the Netherlands, which has a smaller population than the UK, the upper limit is 25 offspring per donor, while in France it is five.