The organisation, International Budget Partnership, has recommended that Fiji publish budget information on government websites as the country has plummeted to the bottom of a list of 94 countries in its 2010 report.
The organisation says it provides the only independent, comparative and regular measure of budget transparency and accountability around the world.
It says Fiji scored zero points out of 100 as it is virtually impossible for citizens to hold the government accountable for its management of the public's money.
The report notes that in the 2008 survey Fiji scored 13 points but since then, the interim regime has clamped down on information.
It says there are now no pre-budget statements, no year-end reports and no audits.
The finance ministry is run by the interim prime minister, Commodore Frank Bainimarama, who seized power in 2006, purportedly to root out corruption in government.
By comparison, the report gives Papua New Guinea a score of 57 and New Zealand 90.
Apart from Fiji, the only countries with a zero score are Equatorial Guinea and Sao Tome e Principe.