The two ruling parties agreed at an executive meeting Wednesday to seek passage during the current Diet session of a bill aimed at giving Japan another tool to impose economic sanctions unilaterally on North Korea.
The bill would empower the government to ban port calls by vessels it designates at a Cabinet meeting as "necessary for the nation's peace and public security."
A port call ban would deal a heavy blow to North Korea because its ships carry not only cargo and passengers, but also hard currency that the economically troubled nation desperately needs.
The Liberal Democratic Party and New Komeito reportedly decided not to set a specific date for submitting the bill to the session, which ends June 16, because they prefer to keep it as a diplomatic card as they monitor North Korean's moves.
Two parties agreed at a meeting of secretaries general and Diet affairs chiefs to set up a working group in the next couple of days to work out the details of the bill, participants said.
LDP Secretary General Shinzo Abe told reporters after the meeting his party will begin moves to submit the bill as soon as it completes arrangements with New Komeito.
New Komeito had been cautious about when to submit the bill but has eased its stance.