But the secrecy bill has quickly become a lightning rod for opponents, many in the news media and at universities, who fear that it gives too much discretion to the nation’s powerful bureaucrats to decide what is a state secret and allows a famously opaque government to provide even less information to the public. Many have warned that the bill could lead to abuses of power by the government, and some critics have gone so far as to compare it to much more draconian prewar laws that placed severe restrictions on speech, and ultimately allowed the military to drag Japan into World War II.

“Japan doesn’t have the strong tradition of freedom of speech, as our recent history shows,” said Yasuhiko Tajima, a professor of media law at Sophia University in Tokyo. “Allowing bureaucrats to declare whatever they want to be state secrets would make us no different than dictatorships like North Korea and China.”

One of the biggest criticisms of the bill is that its definition of secrets is too vague and broad. The current wording gives the heads of government agencies the power to declare information off limits if it touches on such sensitive national security areas as diplomacy, defense and antiterrorism policy. Those found guilty of leaking these secrets could face up to 10 years in prison, far longer than under Japan’s current laws.

The secrecy bill was submitted in tandem with the bill to create a National Security Council that Parliament approved this week.

Political analysts say the twin measures are the first steps in a legislative agenda that could eventually see Mr. Abe try to fulfill his long-held goal of revising his nation’s antiwar Constitution to allow for a fully developed military instead of purely defensive forces — still a controversial idea in Japan.