NGO Watch, a joint project of the American Enterprise Institute and the Federalist Society for Law and Public Policy Studies, targets advocacy NGOs, many of which have opposed US government policy on Iraq or climate change.
The institute, which has close links to the Bush administration, argues that "a loose set of rules governing the accreditation of NGOs has meant that an unelected few have access to growing and unregulated power.
"The extraordinary growth of advocacy NGOs in liberal democracies has the potential to undermine the sovereignty of constitutional democracies, as well as the effectiveness of credible NGOs."
Much of the site is under construction, but many UK-based NGOs are designated for entries.
Among them are Friends of the Earth, ActionAid, the World Development Movement, Minority Rights Group, and Oxfam GB.
Care International and Greenpeace are already profiled. Care International's entry includes reference to its opposition to the Bush administration's policy of denying funding to groups which perform or promote abortion, while the Greenpeace entry lists its actions against corporations such as ExxonMobil.
A spokesman for Greenpeace said: "This lot are accusing us of being unelected and unrepresentative, with suspect funding and too much power. That's some gall from a group that gets its funding from ExxonMobil, has a revolving door arrangement with the White House, and never sought a mandate from anybody outside big business.
"The American Enterprise Institute is closely related to the Republican Party and the current administration in Washington. Fellows include Richard Perle, a member of the Pentagon's defence policy board, Newt Gingrich, former Republican speaker of the house of representatives, and Lynne Cheney, wife of US vice president Dick Cheney. Former American Enterprise Institute vice president John Bolton is now under-secretary for arms control and international security in the US state department.
Dave Timms, press officer at the World Development Movement, said: "We are disappointed that they don't seem to have a full file on our organisation, though we are listed. We'll be sending them information about us. It will be an honour to be on their hate list.
"It would be easy to dismiss these guys as right-wing political oddballs. Unfortunately, the current occupants of the White House take groups like this seriously."
But concerns over the power of NGOs is not limited to Washington. In April, Labour MP Tony Colman said some "claim to be offering the alternative political voice in today's world but the extent to which this is true is questionable."