Ben Bernanke, the chairman of the US Federal Reserve, has launched an attack on the weak infrastructure of the multi-trillion dollar over-the-counter derivatives market, a weakness that he said “exacerbated” the vulnerability of the financial system following the unravelling of Bear Stearns.

In remarks yesterday during a mortgage lending forum in the US, Bernanke called on the participants to improve the efficiency and reliability of the infrastructure across the derivatives markets, much of which is dominated by sophisticated instruments known as credit default swaps.