Congress had demanded the full release by April 30 of a Defense Department examination of perchlorate contamination at all of the agency's 5,000 active and closed military installations.

So far, the agency has revealed results only for about 305 bases.

Initially, Pentagon spokesman Glenn Flood said the report would be about two weeks late. On Friday, officials said the delay will be longer.

"I misspoke," Flood said. "I was led to believe it would be by the middle of May and then the end of May. Now I hear it may be mid-June."

He called the delay strictly procedural, but declined to specify the holdups.

Sen. Dianne Feinstein, D-San Francisco, the driving force behind the congressional demand for the report, has written to Defense Secretary Donald Rumsfeld complaining about the delay.

She also has accused the Pentagon of "consistently avoiding providing information to Congress about perchlorate contamination."

Perchlorate is a naturally occurring and man-made chemical that is the main ingredient in solid rocket fuel.

According to the California Office of Environmental Health Hazard Assessment, perchlorate "does not pose a known cancer risk." Researchers say, however, that it interferes with iodine uptake into the thyroid gland -- thereby disrupting the thyroid function and potentially leading to tumors.

Aerospace-rich Southern California has been a hotbed of perchlorate contamination.

According to the Environmental Working Group, more than 80 percent of the state's 351 perchlorate-polluted water-supply systems are in Los Angeles, San Bernardino and Riverside counties.

Lisa Friedman, (202) 662-8731 lisa.friedman@langnews.com