Holdouts against a settlement of Argentina’s defaulted debt are opening a new front in their campaign for a juicy payout more than a decade after the biggest sovereign default on record.

Lobbyists for some of the investors who hold about $6 billion in Argentine debt are in London to persuade Britain to follow the lead of the United States, which last September decided to vote against new Inter American Development Bank and World Bank loans for Buenos Aires.

Washington believes Argentina, a member of the Group of 20, is not meeting its international obligations on a number of fronts. Apart from the dispute with private bond holders, Argentina has yet to agree with the Paris Club of official creditors on a rescheduling of about $9 billion of debt. It has refused to let the International Monetary Fund conduct a routine health check of the economy. And it has failed to comply with the judgments of a World Bank arbitration panel.

In short, Argentina is not playing by the rules of the international game, says Rob Shapiro, a former U.S. under secretary of commerce, who is now co-chair of the Argentina Task Force America.

According to its website,  the group’s aim is to “vigorously pursue” a “just and fair” reconciliation of the Argentine government’s default in December 2001 on some $95 billion of debt.