WASHINGTON/BOSTON (Reuters) - The International Monetary Fund, the intergovernmental group that oversees the global financial system and brings together 187 member nations, has become the latest known target of a significant cyber attack. A cyber security expert who has worked for both the Washington-headquartered IMF and the World Bank, its sister institution, said the intruders goal had been to install software that would give a nation-state a digital insider presence on the IMF network. Such a presence could yield a trove of non-public economic data used by the Fund to promote exchange rate stability, support balanced international trade and provide resources to remedy members balance-of-payments crises. It was a targeted attack, said Tom Kellerman, who has worked for both international financial institutions and who serves on the board of a group known as the International Cyber Security Protection Alliance. The code used in the IMF incident was developed specifically for the attack on the institution, said Kellerman, formerly responsible for cyber-intelligence within the World Banks treasury team and now chief technology officer at AirPatrol, a cyber consultancy. The attack on the IMF was the latest to become known in a rash of cyber break-ins that have targeted high-profile companies and institutions, often to steal secrets with potentially far-reaching economic implications. The list of victims includes Lockheed Martin Corp, Sony Corp and Citigroup Inc. IMF spokesman David Hawley said Saturday the Fund was fully functional, despite the attack. I can confirm that we are investigating an incident, he said, adding he was not in a position to elaborate on the extent of it. He declined to respond to requests for comment on Kellermans conclusion about the intruders goal. The US FBI is helping to investigate the attack on the IMF, according to a US Defence Department spokeswoman. A World Bank official said the Bank had cut its network connection with the IMF out of caution even though the information shared on that link was 'non sensitive. Rich Mills, a Bank spokesman, said the World Bank Group, like any other large organisation, is increasingly aware of potential threats to the security of our information system and we are constantly working to improve our defences.