An environmental group has described the start of work on the controversial A6 scheme as “highly irregular”.
Friends of the Earth director James Orr made the comment after the Department for Infrastructure confirmed that work is currently taking place on a section of the planned route.
The planned route, close to an Area of Special Scientific Interest and a Ramsar site, which protects internationally important wetland sites, has proved controversial.
A legal challenge is due to be heard.
If completed the project is expected to improve travel times between Belfast and Derry.
In recent weeks hedgerows have been taken out and trees cut down along part of the route close to Randalstown and Toome.
Mr Orr last night said it was “highly irregular for a government department to do this” in light of the pending legal action.
“During judicial reviews once they get through the leave stage, they generally stop everything until they are determined,” he said.
“It’s not good practice."
Mr Orr said that contractors are not allowed to begin any earthworks on the project until the end of March in a bid to protect migrating Hooper swans which feed along the proposed route.
The decision to remove hedges and tress comes weeks before an annual ban on hedge cutting to protect nesting birds comes into force next month.
A spokesman for the Department for Infrastructure said: “The works currently ongoing between the end of the M22 at Randalstown and the Toome Bypass are related to delivery of the A6 Randalstown to Castledawson Dualling Scheme.
“There is no legal challenge to this section of the scheme.”
