The White House ordered tighter security to prevent leaks like the release of more than 250,000 State Department cables. Sunday's release of documents obtained by the whistleblower website WikiLeaks exposed the inner workings of U.S. diplomacy, including candid assessments of world leaders and disclosures on issues such as Iran's nuclear and missile programs.

U.S. authorities also were conducting a criminal investigation of the leak of classified documents, which WikiLeaks provided to five media groups that published reports on them, said a  Reuters report.

The White House condemned the release and said the disclosures may endanger U.S. informants abroad, ordered government agencies to tighten procedures for handling classified information. The new procedures would ensure "that users do not have broader access than is necessary to do their jobs effectively," and would put restrictions on the handling of classified material, the report said.