WASHINGTON (AP) -- Threats to the global economy have lessened a bit in recent months, but policymakers must remain on guard nonetheless, the head of the International Monetary Fund said.

The remarks by IMF chief Rodrigo de Rato come as investors have fretted about the severity of the housing slump in the United States and its impact on the rest of the world.

"Where is the global economy now? I do not think that the risks are greater than they were six months ago. Actually, I think they are a little lower," de Rato said in a speech to the Peterson Institute for International Economics.

Last week, an IMF report concluded that so far the economic slowdown in the United States — the world's largest economy and biggest importer — has had only a small effect on global economic activity. "Central banks around the world have established credibility in taming inflation, and their task has been made easier over the last six months by lower oil prices," de Rato said. "But the risk that political events could disrupt the global economy remains."

So-called "global imbalances" — skewed trade and investment patterns, which are a threat to the world's longer term economic stability, continue, he said. And, an increased willingness by some financial players to take risks "has produced some questionable lending and borrowing," de Rato said.

"If political leaders don't think that global imbalances are important, or are complacent about financial market developments, it is more difficult to persuade them to take the actions needed to sustain global prosperity," he warned.

De Rato predicted last month that global growth for all of this year will clock in at close to 5 percent. De Rato said that would be the strongest five-year span for the world economy since the late 1960s.

Projections will be released this week ahead of the spring meetings of the 185-nation IMF and the World Bank on April 14-15.

"Some of the risks are different, and there is greater consciousness of the uncertainties and paradoxes that lie behind our current prosperity," he said.

On another topic, the IMF chief said the lending institution is moving ahead on plans to revamp itself to better respond to global challenges and to ensure that member countries' voices are heard. "The changes we need won't be easy," he said.

The IMF also is working on a plan on how it can beef up its periodic economic reviews of countries, especially their exchange-rate practices. "Another part of the strategy is to improve our practice, for example, by deepening our analysis of exchange rates and of spillovers between countries and markets," de Rato explained.