A Health and Safety Executive (HSE) report found serious failings in maintaining social distancing while the country is in danger of having a second spike in Covid-19 cases.
The inspection carried out at Quarry House on 27 August, identified a number of breaches under the Health and Safety at work act 1974.
PCS reps worked closely with HSE inspectors to identify the breaches as highlighted in the report .
According to the BBC, the majority of DWP employees in Leeds have been working from home during the pandemic but there have still been hundreds of people in the office.
Responding to the report, general secretary Mark Serwotka said: "The HSE report on the DWP Leeds Office shows that the government has failed staff and the wider community by not adhering to basic health and safety legislation.
"There is a very real danger of a second Covid spike and this incident makes a mockery of DWP's insistence that offices open until 8pm to the public when they can't even maintain social distancing.
"It is unlikely this is an isolated incident and Boris Johnson should re-think forcing thousands of civil servants back to the office when the rate of covid infection in the country is rising significantly."