A Liberal executive decision to charge $199 a head for a convention on the future of the party will limit debate by grassroots members, says Tony Abbott.
Hundreds of Liberal faithful are expected to attend the Party Futures Convention in Sydney from July 21 to 23.
The convention is aimed at finding a consensus on a raft of reforms, including greater member participation and improvements to the way the party campaigns.
One of the key issues will be the system of candidate selection, which reformers say is distorted by the involvement of party executive members and factions.
Mr Abbott is pushing for a "one member, one vote" principle across all aspects of the party in order to give power back to grassroots members.
However, he said the cover charge would ensure the convention would be stacked by "professional Liberals".
"As things stand, it does look like it's an attempt to smother discussion and keep people out rather than let people in," the former prime minister told 2GB radio on Wednesday.
He said it was very discouraging for rank and file members.
"If it stands a lot of people are going to feel cheated," he said.
Prime Minister Malcolm Turnbull told a party meeting last year he wanted the convention to "chart a course to more open policy forums, more frequent and direct access to members of parliament and senators at party meetings, transparent delegate selection and preselection processes in which all members can participate".
