Racial prejudice lay behind more than half the 7,649 hate crimes reported to the FBI in 2004, the bureau said Monday. Hate crimes against black Americans were most prevalent.

The number of race-based incidents rose by 5 percent last year to 4,042 from 3,844. Authorities identified prejudice against blacks in 2,731 of those crimes, the FBI said.

Overall, the number of hate crimes grew by just 2 percent compared with the 7,489 in 2003, and there were slight declines in crimes motivated by bias based on sexual orientation and ethnicity, the FBI said.

The data also showed that crimes against Muslims have leveled off since a spike following the Sept. 11, 2001, attacks. "We tend to see the number of bias incidents go in cycles in large part tied to international events," said Ibrahim Hooper, spokesman for the Council on American-Islamic Relations. "It has leveled off since 9/11, but unfortunately at a higher level than prior to 9/11."

In 2001, there were 481 anti-Islamic incidents. There have been around 150 in the three years since, the FBI said.

Among anti-religious hate crimes, anti-Jewish incidents have long been the most common. Of the 1,374 incidents of religious bias, 954 were directed at Jews, the FBI said.

The information was supplied by 12,711 local law enforcement agencies nationwide covering nearly 87 percent of the U.S. population.

Because the number of police agencies reporting varies each year under the voluntary system established by the Hate Crimes Statistics Act of 1990, officials caution against drawing conclusions about trends in hate crime volumes between years. They say the figures provide a rough picture of the general nature of hate crimes.