U.S. Treasury Secretary Henry Paulson is calling on the International Monetary Fund (IMF) to take a more active role in monitoring the international investments of a growing number of state-owned funds around the world.

Such sovereign funds, backed by cash reserves amassed in China and oil-exporting nations, are believed to be worth over $2 trillion.  The funds' rapid recent growth, and uncertainty about their operations, has led to concern that their investments could be used for political purposes.

Paulson says the IMF is best placed to monitor the growing number of state-backed wealth funds.  He spoke Saturday to finance officials from around the world gathered in Washington for the annual meetings of the IMF and World Bank.

The U.S. Treasury secretary says a tightening of credit policies will limit U.S. economic growth, but he expects global economic growth to continue at a rate of about five percent, for both this year and next.

The global economy has been rocked this year by the slumping U.S. housing market, a decline in the U.S. dollar and rising oil prices.  Paulson says recent volatile trading in financial markets should serve as a reminder to all governments to remain vigilant about short-term economic developments. 

Outside the international meeting Saturday, hundreds of protesters marched to oppose IMF and World Bank policies, which they say exploit poor and developing nations.  Police kept the demonstrators far from the bankers' meeting site.

A similar protest in the capital on Friday night took a violent turn when militants in the crowd threw rocks and bricks through store windows.  One woman was hit in the face by a brick.