Ash dieback is now on 257 sites around the country and forestry experts believe it will gradually spread to most of the UK’s 92 million ash trees.

Mike Seville, Forestry and Woodland Adviser at the Country Land and Business Association, said diseased trees can be a hazard because of falling branches.

It is the responsibility of the landowner, whether the local authority, Highways Agency or private household to deal with the trees.

If they are not dealt with then the owner is open to being sued if someone is injured by a falling branch or tree.

Mr Seville said it will cost on average £500 to make trees safe by employing tree surgeons to take off branches or even fell trees. “As the tree falls to pieces there is going to be some significant costs,” he said.

The cost to councils, the Highways Agency and Network Rail could run into the millions.

It is estimated there are 3.65 million ash trees in Britain in urban areas so the total cost could run into hundreds of millions.

Charities like the National Trust and the RSPB will also have to pay to ensure ash trees do not become dangerous.

Austin Brady, head of conservation at the Woodland Trust, admitted it could be expensive.

He said ash trees in forests will be left alone but trees by footpaths or roads will have to be closely monitored and dealt with if they become dangerous.

“It could be expensive. It depends on how many of the trees are infected and how quickly.”

The disease kills off young trees quickly, but more mature specimens can take years to die.

The Government is currently drawing up an action plan on ash, including how to reduce costs.

For example, by keeping infected trees healthy and allowing ash wood to be sold as fuel.

Ash trees are the third most abundant broadleaf tree in Britain, after the oak and birch.

A total of 19 pests and diseases are now attacking trees in the UK, of which 10 are considered to be at the ‘epidemic stage’. At least a further 11 deadly diseases are a potential threat “on the horizon”.

All information sourced from The Telegraph Website.