Forestry officials in Norfolk have welcomed new plans to save the red squirrel - by targeting its number one enemy. Populations have become so low that the distinctive bush-tailed creature has not been spotted in Thetford Forest for more than two years.

Forestry officials in Norfolk have welcomed new plans to save the red squirrel - by targeting its number one enemy.

Populations have become so low that the distinctive bush-tailed creature has not been spotted in Thetford Forest for more than two years.

But scientists are set to provide a lifeline for the red squirrel with proposals to develop a contraceptive to shrink the grey squirrel population, which is slowly taking over Britain's woodland areas.

Neal Armour-Chelu, district ecologist for the Forestry Commission, said Thetford Forest's once thriving red squirrel colony was almost extinct because of a deadly virus carried by its grey cousin.

"We have not had any genuine reports of red squirrels in the forest for the past two years, because the greys, which are the stronger of the two and survive better over winter, have taken over," he said.

"Grey squirrels spread and spread, but there

are some places where there are still red squirrel populations, and therefore there are opportunities

to maintain a buffer between the two species.

There are now only around 140,000 native red squirrels left in the country compared to 2.5m greys, which arrived in the UK from North America in the 19th century.

The Forestry Commission is attempting to manage woodlands to help the under treat species, but scientists are now exploring a new drug to stop grey squirrels from spreading.

Biodiversity minister Jim Knight announced plans earlier this year to conduct a massive cull of the non native animals.

Trials on a squirrel contraceptive were halted in 2002 because of inconclusive results, but Mr Armour-Chelu said the fresh sterilisation plans could promote a resurgence of red populations in Thetford.

"It is going to take a lot of hard work and investment, but it is something we are keen to do because it is a great pity that, as far as we know, there may only be one or two red squirrels left in the forest."

He added that the Forestry Commission would continue to supporting and encourage the humane control of grey squirrels, as well as monitoring the damage they cause and the threat they pose to woodland management.