Campaign groups urging Britons to vote to leave the European Union in next month’s referendum raised more funds than those advocating continued membership during the 12-week period ended in late April, the UK’s elections watchdog said on May 11.

The disclosure, covering the period from February 1 through April 21, gave voters their first official glimpse of who is funding the debate; three more disclosures are due over the next two months. There is no requirement for donations made before February 1 to be disclosed.