TOKYO (AFP) - Japan's Lower House of Parliament is set to pass a controversial new state secrets Bill on Tuesday, which critics say is draconian and will impinge on press freedom and the public's right to know.

After a morning of debate, a special House committee gave the green light to the Bill, which would give Tokyo far broader powers in deciding what constitutes a state secret, and severely punish those who leak the information.

"It is an urgent task to prepare for legislation that should remain secret at a time when fears over information leaks are growing," Prime Minister Shinzo Abe told the committee.

The hawkish Premier insisted that the Bill would neither restrict freedom of the press nor encourage the authorities to "arbitrarily" designate information as restricted.

"Frankly speaking, there is misunderstanding," Mr Abe said. "I want to firmly say that it is obvious that normal reporting activity of journalists must not be a subject for punishment under the Bill."

Local media said the committee, dominated by his ruling coalition, was always likely to give the nod to the legislation, clearing the way for a vote in the full chamber later in the day.

Mr Abe's ruling coalition, which controls both the Lower and Upper houses, aims to enact the Bill by Dec 6, when the current Parliament session ends, despite growing concerns among major opposition parties and the public.

Thousands of demonstrators have hit the streets to register their anger at the Bill, which comes amid worldwide debate over government secrecy in the wake of the Edward Snowden affair.

Under the proposals, information related to defence, diplomacy, counter-intelligence and counter-terrorism can all be classified as a state secret, at the behest of politicians.

Critics argue that the bill could mean far more information being kept from the public, with little real oversight.

The legislation is aimed at plugging Japan's notoriously leaky bureaucracy after years of complaints from chief ally the United States, which has been reluctant to pool information.

If the law is passed, public servants who give away state secrets could be jailed for up to 10 years. The present maximum is one.

Official intelligence-gathering has come under the spotlight since former Central Intelligence Agency employee and National Security Agency contractor Snowden fled to Hong Kong with a trove of classified US documents about surveillance programmes.