Japan has failed to create a revamped nuclear regulatory agency by the promised date _ April 1 _ amid political infighting, raising questions about its commitment to bolstering oversight after last year's nuclear crisis.

Authorities have been accused of lax supervision of Japan's 54 nuclear reactors after a massive earthquake and tsunami led to a meltdown of three reactors at the Fukushima Dai-ichi plant in the world's worst nuclear disaster since Chernobyl.

Prime Minister Yoshihiko Noda's Cabinet has endorsed a bill to create a more powerful and independent regulatory body that would unify various nuclear safety and regulatory agencies.

But progress has been slowed by disagreements over how much independence it should have and by other disputes.