Britain issued new guidelines on Tuesday to protect frozen sperm, eggs and embryos stored in fertility clinics from being accidentally destroyed.

The Human Fertilisation and Embryology Authority (HFEA), which licenses and monitors fertility clinics, said new storage rules follow a number of incidents in which patients’ stored material thawed because of inadequate temperature controls.

“We have to make sure we take every step possible to safeguard stored material in clinics. For cancer patients in particular, this material is so precious because it can be their only chance of having children,” said Angela McNab, chief executive of the HFEA.

Under the guidelines, all clinics storing frozen sperm, eggs and embryos must have an alarm and monitoring system fitted to storage vessels by June 2005. It will alert staff if problems occur outside working hours.

Emergency procedures must also be in place in case of a temperature problem, along with a staff “on-call” system.

The HFEA also said samples from patients having medical treatment that can leave them infertile should be divided and stored in different containers.

“Patient safety is our top priority at the HFEA and we work constantly with infertility clinics to improve it,” McNab added in a statement.