Anticorruption activists have urged President Obama to back a plan to publicly register the owners of shell companies in the United States and around the world, a move they say is essential to thwart corrupt government officials, tax evaders and money launderers who rely on an opaque financial system.

The plan, backed by Prime Minister David Cameron of Britain this year, was outlined in letters sent to Mr. Obama last week by two groups of current and former prosecutors and activists. The issue is set to be raised again at the Group of 8 summit meeting of industrialized countries this month.

“Corrupt politicians, tax evaders, and organized criminals all use complex webs of shell companies to hide and launder stolen money,” said 19 prosecutors and activists in one of the letters. The group calls for “governments to require existing company registers to collect information on the ultimate owners of all companies” and for that information to be publicly available.

France and Italy are also thought to back the proposal, said Stefanie Ostfeld, a senior policy adviser for the anticorruption research group Global Witness, but while the United States has expressed an interest in such information being made available to law enforcement officials, it has appeared reluctant to make it public.