Robbie LeBlanc has resigned as director of the European branch of People for the Ethical Treatment of Animals just over a year after taking the job.
LeBlanc joined the campaigning organisation in June 2008 after spending 10 years as an accountant at Guardian News and Media.
Poorva Joshipura, director of special projects at the charity, said LeBlanc had decided to resign some time ago. She said his duties would now be shared between herself, the charity's office manager and its managing director, Ingrid Newkirk.
LeBlanc told Third Sector he had no definite plans about what to do next. He said: "The decision to leave was difficult, but I will remain very active as a volunteer and supporter. Peta is a wonderful organisation and I am very proud of the work it does."
Joshipura said Peta Europe, which currently employs 15 people, had recently carried out a restructuring process because the recession had forced it to focus more on web-based outreach. She declined to say whether there had been any redundancies.
She said the organisation was in the process of seeking charitable status. The Peta Foundation, which produces humane education materials, is already a registered charity.