FitzGibbon Media, which has offices in Washington DC, New York, San Francisco and London, was forced to close last week over allegations relating to the personal conduct of founder Trevor FitzGibbon.
The news was first reported on The Huffington Post, which revealed that a number of female staff had come forward with complaints against FitzGibbon.
The agency works for some of the biggest progressive organisations including Amnesty International, Wikileaks and The Guardian.
A former employee at FitzGibbon told PRWeek: "It’s ironic that we are supposed to be fighting on behalf of these issues, it’s a poor show. The way it has been handled is uncool, our emails were cut off immediately and there has been no severance pay for anyone. It sucks that people are out of a job just before Christmas."
In a statement to The Huffington Post last week, FitzGibbon said: "It is with tremendous regret that we had to close FitzGibbon Media.
"The allegations against me are a distraction to the mission at hand. In order to do what is best for the company, I took a leave of absence. However, it is abundantly clear that an irreconcilable difference has arisen between the FitzGibbon team and me. We had no choice but to make the difficult decision to close FitzGibbon Media.
"I apologise to my team and our clients for the impact this closing will have on them. I will work to once again regain the trust that was lost."
FitzGibbon opened in the US in 2008 and launched its London office in January this year.