Nobel economics laureate Joseph Stiglitz has quit a committee set up by Panama’s government to study the country’s financial system following the leak of a trove of data about offshore accounts set up by a Panamanian law firm.

Panama’s foreign ministry said Saturday that Stiglitz resigned over “internal differences” that it did not explain. Swiss law professor Mark Pieth also resigned.

The committee of experts was set up in April following the international uproar over the leak of the so-called “Panama Papers” revealed details on offshore accounts that helped foreigners shelter their wealth.

The panel is supposed to give recommendations on making it more difficult for people to use Panama’s financial services sector for illegal activities.

Four experts continue to work on the committee.