The Census Bureau has confirmed that, despite widespread impressions to the contrary, it provided information during World War II that helped the War Department locate Japanese-Americans (Nisei) for internment in special camps.

The bureau said that it did not provide names of Japanese Americans, but it did tell the War Department where heavy concentrations of them were living, which was sufficient for roundup purposes.

The information about the bureau's role came to light in a recent letter from Census Director Vincent P. Barabba to Raymond Okamura of Berkeley, Calif.

It contradicted the general impression left by statements from Barabba and other Census Bureau officials over the past year. They held that the bureau had resisted efforts by the War Department to obtain names in the burst of anti-Japanese feeling after the attack on Pearl Harbor.

The statements by Barabba and others were an attempt to reassure persons of Hispanic origin that even if they were here illegally, they could feel safe about allowing themselves to be counted in the 1980 census. They were told that their names would be kept confidential and not turned over to immigration officials.

Barabba's letter to Okamura makes clear that while the statements may have been technically correct, they were misleading.

In 1942, according to the letter, the Census Bureau's data on communities with heavy concentrations of Japanese Americans made it easy for the War Department to round them up and ship them off to internment camps.

"Following the events at Pearl Harbor in December 1941," Barabba wrote, "a bureau statistician was assigned to the West Coast to assist in the statistical work of the War Relocation Authority. Officials at bureau headquarters prepared a duplicate set of punch cards which were used to tabulate information on the geographic concentrations of Japanese Americans, primarily in California.

"These cards contained no names or other identifiers for individuals, but provided sufficient geographical information to use for planning purposes in the evacuation program." The information showed "distribution of persons of Asian ancestry by counties and minor civil divisions."

A census official, commenting on the letter which Okamura made available to The Washington Post, said a minor civil division might include a town of 1,500 or a tract within a city. The official said Census Bureau cooperation with the War Department was well-known in the Japanese community.

According to Barabba's letter, a 1929 law barred the Census Bureau from revealing information about a specific individual. But it did not bar the bureau from releasing the type of statistical information that it did. So, he concluded, the bureau had acted within the law.

However, Barabba further asserted in the letter that, in fact, Congress in the 1942 War Powers Act suspended for the duration of World War II even the 1929 confidentially statute. Therefore, the bureau would have been within the law if it had listed Japanese Americans by name. But Barabba said there is no indication that the War Department bothered to ask for the names, because the geographic material was sufficient for its purposes.