Dismal summer weather could be responsible for an increase in rickets among British Asians, Manchester-based scientists have warned.

Skin experts at Manchester University said the bone disorder - caused by a lack of vitamin D - is on the rise among people of South Asian descent due to a lack of sunshine.

Lesley Rhodes, professor of dermatological sciences at Manchester University, said: "The past two summers have seen below-average levels of sunlight in the UK and this has coincided with a resurgence of rickets, especially among those of South Asian descent.

"The pigment in darker skin reduces some effects of sunlight so that larger amounts are required to produce adequate vitamin D levels, putting this group of the population at greater risk.

"Studies are ongoing to define how much sunlight is required for lighter-skinned people to make adequate amounts of vitamin D in their skin - but very little is known about the sunlight requirements of South Asian people."

The University of Manchester Photobiology Unit has now launched a study to discover what levels of sunlight exposure are needed to provide sufficient vitamin D for people with South-Asian skin.

The researchers, funded by Cancer Research UK, are seeking healthy volunteers whose families originate from India, Pakistan or Bangladesh, and are living in Greater Manchester, to take part in the study.