"The politics around Brexit are the biggest risk to Brexit. The government is clearly in a situation where they are trying to deny the complexity of it," FDA General Secretary Dave Penman told The Guardian newspaper.
The First Division Association is a union for the Britain's senior public servants, representing 18,000 senior managers, policy advisers, diplomats and other professionals working across the government and the National Health Service.
"The civil service is either going to have to be given more resources to deal with Brexit and its usual work or it will have to change its priorities. And government doesn’t want to admit to either," he was quoted as saying by the newspaper.
In June, the United Kingdom voted in a referendum to leave the European Union. Soon after the referendum, May said the country would trigger the Article 50 of the EU Lisbon Treaty by the end of March 2017, thus beginning the withdrawal negotiations.