The Landmark Trust and Heritage Link, a support group for heritage bodies, separately approached the chief executives' body to ask for a forum in which heritage charities could discuss matters of specific interest.
Kate Pugh, speaking on behalf of Heritage Link, said: "We recognise that we are just an element within the whole of the third sector, and we need to raise awareness of heritage issues.
"The current focus on charities that are involved in public service delivery benefits health and social care organisations but not heritage-related ones," she said.
Peter Pearce, director of the Landmark Trust, raised similar concerns.
"The charities that are providing public services for the Government tend to have different priorities from those more traditional charities that are doing campaigning and fundraising activities," he said.
"A special interest group would allow us to discuss issues that are not of interest to other charities."
Pearce added that, although Heritage Link had already done an "enormous amount of good" in promoting the heritage cause, anything that strengthened the voice of the heritage sector was to be encouraged.
Gail Scott-Spicer, deputy chief executive at Acevo, said that the grouping was a member-driven initiative. "A couple of our members have said they would like to have a special interest group for heritage charities within Acevo," she said. "We are looking to see what our members need, and will meet to discuss it."
Britain's largest heritage charity, the National Trust, said that it was not so far involved with the proposals.