Denmark's liberal sperm donation laws are being scrutinised after a donor passed a genetic disorder to several children whom he had fathered anonymously.

The Copenhagen clinic where the man donated the sperm said that he had passed on the nerve disorder neurofibromatosis type I to five children, after a screening test failed to pick up the condition, which can cause tumours on the optic nerve.

Peter Bower, director of the Nordisk Cryobank, told Agence France-Presse he was certain that in the five cases, the disorder had come from the sperm donor, even though the genetic mutation is not always transmitted and can appear by itself. Symptoms vary but can include skin discoloration, high blood pressure, tumours on the optic nerve and bone deformity.

"Prior to October 2009, this donor has provided sperm to 10 countries inside and outside Europe," said Mr Bower, adding that he could not give further details about where and when babies were born. Danish media reported that 43 children had been born using the donor's sperm. It is unclear whether the others have all been tested for the disorder.

Denmark has some of the most liberal laws on sperm donation, and sperm banks in the country ship samples to clinics across the world. Unlike in the UK and most other countries, in Denmark men can provide sperm without identifying themselves, and prospective clients are able to browse the anonymous fathers online through categories such as height, eye colour and educational qualifications.

Nordisk Cryobank has been criticised for failing to withdraw samples from the donor in question when it became apparent that there could be a problem.

Nordisk Cryobank says that it pays 300 kroner (£32) per successful sperm donation, and that it accepts 95 per cent of donations. Denmark's main health body said that from 1 October it will limit the number of pregnancies possible from any given sperm donor to 12, and also stop the use of sperm from any donor under suspicion of passing on genetic conditions.