The pair resigned on Friday from the committee, which the Panamanian government set up in a declared bid to reform the country's tarnished financial services after the "Panama Papers" scandal erupted in April.
Stiglitz, a professor at Columbia University in New York who won the Nobel Prize in 2001, told AFP yesterday that he was "shocked" and "very disappointed." The pair had been "very reluctant to resign," he said.
"In our first meeting we made it clear that we couldn't proceed unless there was a commitment from the government to make our report public and it refused to make that commitment," he said.
In a statement, Stiglitz and Pieth said they believed restrictions on defining the scope of their work, on speaking freely and on guarantees that the report would be released were "tantamount to censorship."
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In April, media outlets published details of murky offshore financial dealings gleaned from 11.5 million leaked documents from a Panamanian law firm -- the so-called "Panama Papers."
The leaks put a host of high-profile politicians, celebrities and sports stars in the hot seat over their assets in tax havens.
It was scheduled to report to Panama's president and government by the end of 2016. Stiglitz was named as its head.
"The vice president flew up to New York to Columbia to try to talk to me, to persuade me to participate in this," he told AFP in a phone interview.
"It seemed as if there was a real commitment," he said.
"I think they were trying to respond to the fire that was raging and may not have thought about how they managed some of the domestic politics," he said.
On July 29, Stiglitz said they were told the government would not provide the necessary assurances, and attempts to intercede with the vice president and president through intermediaries "got nowhere.