The civil service is woefully understaffed to cope with Brexit, the Public and Commercial Services union has warned as Article 50 is triggered.

Government bodies are struggling to maintain existing services after almost seven years of spending cuts, according to the union’s spokespeople. They allege that key areas of the civil service will not be able to manage the demands of Brexit and many departments and agencies are underprepared for withdrawing from the EU.

The union’s view was supported by a recent National Audit Office report that found departments “do not know what skills they have, whether these are in the right place, and what additional skills they need”.

For example Defra, whose work is heavily shaped by EU money and legislation but is among the worst hit in Whitehall by UK government cuts, will “need legal, economic and sector experts to deal with the implications of Brexit”, the NAO said.

“They will have to do this while using their remaining staff to achieve pre-existing priorities,” it added.

Since 2010, the civil service and its related bodies have axed 110,000 posts (21%) and spending reduction plans kept in place by the current government would lead to tens of thousands more in the coming years.

PCS general secretary Mark Serwotka said: “As the government triggers Article 50 it is clear to everyone that the civil service is woefully understaffed and underprepared for Brexit.

“While we engage in the long, complex process of withdrawal from the EU, there will be no let-up in the demand for existing services. All cuts plans must be halted immediately to allow us to properly discuss the staffing and resources that are needed.”