New research to analyse a deadly virus which affects red squirrels is due to get under way at a traditional stronghold for the animal where numbers have plummeted by as much as 90 per cent due to the disease.

The study, at Formby, Lancashire, aims to uncover how the well-loved mammal becomes infected with squirrelpox and whether any have survived infection or show immunity to the virus.

The aim of the research, based at the University of Liverpool, is to help secure the future of red squirrels, which have seen numbers tumble in recent years and have been pushed from much of their range onto islands and isolated pockets in England.

The study will also look at the role grey squirrels, a species which was introduced in the 19th century from America and which has out-competed the smaller red squirrels, play in transmitting the disease - which they carry but which does not affect them.

Researchers want to help prevent further spread of squirrelpox and even enable affected populations recover.

The site at Formby, managed by the National Trust, has seen numbers of red squirrels drop from 200 to an estimated 20 since an outbreak of squirrelpox took hold in November 2007. The Sefton coast area has seen the red squirrel population drop from 1,000 to around 100 in the past two years, the National Trust said.

Anecdotal evidence suggests the population at Formby has stabilised in the wake of the outbreak of squirrelpox and monitoring work will take place this autumn to establish current numbers and the condition of the survivors.

Research will also examine how fast the infection progresses and what can be done to halt its spread.

Andrew Brockbank, National Trust property manager at Formby, said: "Red squirrels would feature on many people's list of favourite British wildlife and we hope that this exciting new project may help secure their future.

"The recent major outbreak of squirrelpox presents a unique window of opportunity for research and the tragic loss of red squirrels at Formby could ultimately provide insights which help red squirrel conservation in the future."

Mike Begon, of the University of Liverpool, who is supervising the PhD study, said: "Formby is on the front line in the battle for survival between red and grey squirrels. We are hopeful that this new research will help us understand the dynamics of squirrelpox virus and how that knowledge can be used to ensure the long-term survival of red squirrels across the UK."