Thorny disputes over whose trees are to blame for subsidence are now being resolved by North-East gene detectives with a technique more commonly used to finger criminals.

Newcastle University scientists have unveiled DNA fingerprinting service used to help insurers identify trees that are responsible.

Often disputes can last for several years, as when two trees of the same kind grow in an area it is very difficult to find out which one is behind the problem.

This is because their roots, which can grow underneath a house and cause the subsidence, may stretch for several metres in different directions. The scientists have now set up, Bioprofiles Ltd, the first company of its kind in the UK to offer this service.

It will be working for aboriculturalists, tree specialists, and building surveyors, as well as insurance companies.

Company director Kirsten Wolff (OK) said: "Houses built on clay are particularly at risk from subsidence, and more so in times of drought. "Tree roots suck water out of the ground, which causes the clay supporting the house to dry out and contract.

"We would typically get involved in a dispute over which tree is responsible for the subsidence, especially when both the householder and his or her neighbour own trees which are equally likely to have roots spreading under the subsiding house.

"We try to establish which tree is to blame and thus indicate which insurance company should pay out."

Dr Wolff, Reader in Evolutionary Genetics at Newcastle University's School of Biology, and fellow scientist and company director Dr Marie Hale, begin their work by taking samples from the suspect trees and the root causing the subsidence. The team then employs three methods of genetic analysis in the laboratory to compare the samples - depending on how difficult identification is.

Dr Wolff, who has carried out similar techniques for plant growers eager to protect their breeding rights, said: "This technique is particularly significant for insurance companies or building surveyors acting for people who live in London and the South of England or affluent areas generally, where house prices tend to be much higher and claims are therefore much bigger."