Prime Minister Shinzo Abe will postpone until next spring a decision on whether to alter the government's interpretation of the Constitution to allow Japan to engage in collective self-defense, amid wariness in junior coalition partner New Komeito, a government source said Saturday.

It is now considered difficult for the Abe administration to stipulate its policy of scrapping Japan's self-imposed ban on collective self-defense in a new basic defense program to be compiled by the end of the year. Exercising the right would enable Japan to go to the defense of an ally under armed attack.

Abe's ruling Liberal Democratic Party and New Komeito had explored holding talks to narrow their differences on the war-renouncing Constitution, but these meetings will now also be deferred, the source said.

With New Komeito remaining reluctant to amend the constitutional interpretation of postwar governments to permit the exercise of collective self-defense, a close aide to Abe attempted to downplay the issue, saying it is "not an urgent matter."

The LDP-New Komeito coalition is expected to postpone a conclusion on the matter at least until the fiscal 2014 budget clears the ordinary Diet session that will convene in January. The ruling camp also aims to prioritize the enactment of a bill that would impose tougher penalties on public servants who leak national secrets, the source said.

New Komeito plans to hold discussions with the LDP on collective self-defense once Abe's panel of experts compiles a report on the issue.

The 14-member panel is expected to urge the government to change its constitutional interpretation so Japan can engage in collective self-defense. But although it is aiming to draw up a report by yearend, the discussions appear to be lagging behind schedule.