Dr Maureen Dalziel, according to a statement released by the Human Fertilisation and Embryology Authority (HFEA), will be leaving immediately at the request of chairman Suzi Leather.

I can assure you that there are no implications of personal impropriety and the matter is not related to the authority's investigation of incidents at licensed centres

Suzi Leather, Chairman, HFEA

The reason behind the vote has not been made public.

Dr Dalziel has only been in post a matter of months.

However, Ms Leather said: "I can assure you that there are no implications of personal impropriety and the matter is not related to the authority's investigation of incidents at licensed centres."

Changes afoot

Dr Dalziel - an expert in public health - is a former regional director of public health and medical director of North Thames Region, as well as former chief executive of the Hillingdon Health Agency.

A stand-in chief executive, Angela McNab, has been appointed on an interim basis until the post can be filled.

The HFEA is in charge of making sure that the UK's fertility clinics stick to strict rules governing the way they carry out treatments.

The authority has come under recent pressure over high-profile mistakes involving eggs, sperm and embryos which left women carrying the wrong embryos, or embryos formed using the wrong sperm and eggs.

The HFEA recently proposed an increase in its own budget from �1.5m to �4m, with the extra being funded by a rise in charges to fertility clinics.

A consultation document said that its present budget was no longer enough to allow it to fulfil its role properly.