The leadership of the C20 - a diverse international group of charities, aid agencies and community organisations linked the G20 - has been told it will be given only three or  four accreditations to the G20 media centre. At last year's G20 summit in St Petersburg, the C20 was given 75 media centre accreditations and at the 2012 summit in Los Cabos, Mexico, 100 accreditations were granted.

Tim Costello, chief executive of World Vision Australia and chair of the C20 in 2014, said he could not understand the decision to reduce the access of civil society groups to the Brisbane event.

"We had very good access to the summit in St Petersburg and civil society is playing constructive role," he said. "We call for more access in Brisbane. If you want civil society interpreting the meaning of this high financial architecture, you have to give civil society greater access to it."

The prospect of a very small number of accreditations for the C20 has raised concern in the community sector that the Australian Government, which is president of the G20 this year, is attempting to shut down media scrutiny of the Brisbane summit.

"If Russia can provide 75 accreditations for civil society groups to watch the proceedings on the G20 close up, surely a country with the proud democratic traditions of Australia can do better than three," said one source from the sector who did not want to be named. "This is about openness and transparency."

A spokeswoman for the Department of Prime Minister and Cabinet's G20 Taskforce said the primary purpose of the media centre is to support and accommodate up to 3000 media workers expected to register for the G20 summit. She said "associated bodies such as the C20 will be granted appropriate access to the G20 facilities including the media centre".

But Fairfax Media understands representatives from at least three G20 member countries have requested the Australian Government  allow greater access for their non-government organisations during the Brisbane summit.

The summit, on November 15 and 16, will be the most significant meeting of world leaders Australia has ever hosted. Up to 7000 international delegates and media workers are expected in Brisbane for the event.

In a speech in Washington this week the Treasurer, Joe Hockey, said the G20's "public messaging" had to improve.

"Our actions had to be understood and resonate with all members of the community – not just the technocrats," he said.

"So we've worked really hard to convey our outcomes in short, non-technical documents that are easily understood. We have also worked hard on our relationships with key stakeholders, including business and community representatives. This goes beyond traditional discussions to more meaningful engagement on the agenda."

But following the speech, one civil society sector source asked: "How does shutting out community groups from the G20 summit fit with that rhetoric?".