WASHINGTON — Daniel Ellsberg, the former Defense Department official who leaked the Pentagon Papers during the Vietnam War, is urging government insiders to provide similar classified documents about the invasion of Iraq.

Joined by other whistle-blowers and former government employees, Ellsberg said at a Sept. 9 news conference that claims of government deception and lies have “little credibility” unless supported by documentary evidence, which often is available only in classified materials.

The document that came to be called the Pentagon Papers was a 7,000-page study of U.S. decision-making in Vietnam that was classified “top secret.” Ellsberg leaked the study to the Senate Foreign Relations Committee and later 19 different newspapers. The New York Times began publishing them in 1971. The publication added fuel to an already politically charged debate over U.S. involvement in Southeast Asia and set legal precedents for freedom of the press.

In a memo to current government employees, Ellsberg and other former government officials said federal insiders owe a “higher allegiance” to the Constitution, the public and American soldiers in Iraq than to their government bosses.

“A hundred forty-thousand Americans are risking their lives every day in Iraq for dubious purpose,” the memo said. “Our country has urgent need of comparable moral courage from its public officials. Truth-telling is a patriotic and effective way to serve the nation. The time for speaking out is now.”

The memo acknowledged that whistle-blowers risk personal setbacks, such as losing their jobs, but urged them to act nonetheless. “You may save many Americans from being lied to death,” it said.

Sibel Edmonds, who was fired by the FBI after she alleged security lapses in the agency’s translator program, said the government frequently over-classifies documents, including the investigation into her own case.

Among the documents claimed to be wrongly classified are sections of reports from Army investigations into prisoner abuse in Iraq and Afghanistan, and supporting material for then-Army Gen. Eric Shinseki’s February 2003 estimate that several hundred thousand troops would have to stay in Iraq after the war.

Ellsberg was a special assistant to the assistant secretary of defense during the Vietnam War. He released the 7,000 page classified study to the Senate and 19 newspapers in 1971 and now leads the Truth Telling Project.