Conservative County Council candidate Richard Wearmouth said: "On Wednesday (1 February) morning I arrived at County Hall to find the council trying to cut yet more trees down on the Queen Elizabeth Avenue.
"Together with local residents and other local politicians I argued with the chief executive and the legal officer about the felling. I told the council that our reading of the felling licence regulations was that they needed permission to fell trees from the Forestry Commission."
He added: "We quickly managed to make contact with the Forestry Commission to ask them to visit the site and stop the work. With this confirmed we informed the council that the Forestry Commission were looking into the matter that day."
A Forestry Commission representative told Horticulture Week: "Forestry Commission woodland officers have visited the site at County Hall in Morpeth and, while they investigate whether there has been a breach of felling regulations, we have advised Northumberland County Council not to fell any more trees."