Australia's Treasurer Josh Frydenberg issued the media release:

Today Australia hosted a call with the Finance Ministers of the United States, the United Kingdom and New Zealand.
This call built on our discussions from last year, to share experiences managing the COVID‑19 crisis.
During the call we exchanged views on our policy responses, and discussed our respective fiscal positions and strategies to support a robust economic recovery.
We agreed to remain in regular contact as a group and will continue to work together in responding to the challenges we face.

OK, so the attendees were (along with Josh):

  • Janet Yellen, US Treasury Secretary
  • Rishi Sunak, the UK Chancellor of the Exchequer
  • And Grant Robertson, the New Zealand Finance Minister