WASHINGTON, July 18 (Xinhua) -- U.S. Federal Reserve Chairman Ben Bernanke said Wednesday that the U.S. economic growth rate for2007 is likely lower than expected.

    The economy is expected to expand between 2.25 and 2.50 percent this year, lower than the pace of 2.5 percent and 3 percent projected in February, Bernanke told the House Financial Services Committee while delivering a midyear Fed economic report to Congress.

    The difference between the new and old forecasts is largely the result of weaker-than-expected residential construction activity this year, he said.

    For 2008, the economy should pick up and expand between 2.50 and 2.75 percent, said the Fed chief.

    "Overall, the U.S. economy appears likely to expand at a moderate pace over the second half of 2007, with growth then strengthening a bit in 2008 to a rate close to the economy's underlying trend," Bernanke said.

    The unemployment rate, currently at 4.5 percent, is anticipated to rise as high as 4.75 percent this year and keeps steady at 4.75percent in 2008, he said. That is unchanged from the central bank's forecast in February.

    On inflation situation, Bernanke said that "core" inflation, which excludes volatile energy and food, is likely to increase by 2 percent and 2.25 percent this year and by 1.75 percent to 2 percent in 2008, the same as the previous projection.

    Bernanke said that one risk to the economic outlook is that the ongoing housing correction might prove larger than anticipated, with possible spillovers onto consumer spending.

    "Another risk is that energy and commodity prices could continue to rise sharply, leading to further increases in headline inflation and, if those costs passed through to the prices of non-energy goods and services, to higher core inflation as well," he said.

    The Fed "has consistently stated that upside risks to inflation are its predominant policy concern," Bernanke said.