The largest leak in the history of the offshore finance industry offers a glimpse into the damage done to developing economies and their resources due to exploitative tax practices.

Civil society organizations are seizing on the leak as an occasion to renew calls for the world’s donors to protect developing countries’ domestic resources from exploitative tax havens and shell companies, such as the more than 210,000 entities created by Panama-based wealth management firm Mossack Fonseca, according to documents released Saturday detailing transactions of its more than 200 wealthy clientele.

Many in the aid community are looking to the government of the United Kingdom for action to curb tax avoidance. More than half of the shell companies listed in the leaked documents are based in British territories. ActionAid reports that tax avoidance costs developing countries more than $200 billion annually in lost tax revenue.