WASHINGTON -- An expanded security forum has taken root in the Indo-Pacific region, a US commission reported Thursday, despite consistent US government denials of any attempt to broaden the so-called Quad.

The US-China Economic and Security Review Commission claimed China's increasingly assertive behavior has led to an increase in cohesion among the countries participating in the multilateral forum, known as the Quad, initially consisting of the United States, Japan, India and Australia.

"Notably, for the first time the grouping also took on an expanded format, known as the 'Quad Plus,' which saw Brazil, Israel, New Zealand, South Korea and Vietnam participating in various group discussions," said the annual report submitted to the US Congress.

The assertion, however, is based on reports from a single Indian news outlet about a series of discussions between the countries this year to jointly tackle the COVID-19 pandemic.

US Deputy Secretary of State Stephen Biegun has noted the COVID-19 discussions have been extremely helpful and that the participating countries in the talks may represent a "natural grouping" of countries that could be part of a Quad Plus meeting when and if such a meeting is established.

"You know the strongest institutions in Asia oftentimes are not inclusive enough, and so there is certainly an invitation there at some point to formalize a structure like this," he said earlier.

South Korea has said the COVID-19 meetings were just that, and that it has never been formally invited to join the Quad or Quad Plus. (Yonhap)