The number of sites harboring a disease decimating Britain\'s ash trees has doubled in a month as the country battles the deadly fungus, researchers say. The number of infected sites has reached 291, prompting Environment Secretary Owen Paterson to announce a national plan intended to control Chalara Fraxinea, responsible for so-called ash dieback disease, The Guardian reported Thursday. A ban on the import or movement of ash trees will remain in place, he said, adding the government is considering appointing a \"tree czar\" to serve as the country\'s chief plant health officer. \"The plan I have set out today shows our determination to slow the spread and minimize the impact of Chalara,\" said Paterson, who acknowledged last month the impossibility of complete eradicating the fungus. \"It will also give us time to find those trees with genetic resistance to the disease and to restructure our woodlands to make them more resilient.\" The fungus, first seen in Britain in February in a tree imported from the Netherlands to a nursery in Buckinghamshire, has now been identified at 136 sites linked to imported plants and a further 155 sites in the wild. The government\'s plan to deal with the fungus has met with some criticism. \"The limited actions and weak commitments set out in the plan will not be enough to control the spread of the disease -- it\'s far too little, too late,\" Simon Pryor, director of the natural environment at the National Trust, said. \"We are alarmed to see the government is even wavering about continuing its program of tracing, testing and destroying infected young ash trees. It is also disappointing to see the government is proposing almost no action in areas of the country already infected.\"