Tom Sharman, policy co-ordination officer at the charity, opposed the party's idea of 'aid vouchers', which people in developing countries could redeem against services delivered by aid agencies and NGOs, saying it categorises aid agencies as service providers.
Andrew Mitchell, the shadow international development minister, gave his support to the scheme at the Conservative Party conference in Bournemouth last week. "I want to see poor people as masters and owners of the international development system, and not as passive recipients," he said.
But Sharman warned that vouchers were not the best way to take things forward. "The scheme sees NGOs as service providers rather than campaigning organisations," he said. "It will be expensive to administer and it's not clear that you'd have a genuine choice of provider."
Sharman argued that a "patchwork quilt" of providers would be unsustainable.
"What happens when they withdraw from that area?" he said. "They're not going to stay there forever."
But ActionAid welcomed Mitchell's announcement about plans for an independent watchdog to investigate aid agencies.
Mitchell told the conference that aid agencies should be subject to independent evaluation, not just self-evaluation as at present.
"We have asked our policy group to consider setting up an international aid watchdog," he said. "This would provide an objective evaluation of British aid."
The Conservative Party is working with charities to develop its international aid policies through the Globalisation and Global Poverty Challenge - a commission set up by Tory leader David Cameron last year. Bob Geldof is among its advisers.