Japan has approved a controversial official secrets law that prime minister Shinzo Abe says is crucial to strengthening national defence but which was bitterly opposed by journalists, academics and many ordinary Japanese.

As protesters chanted outside parliament, the upper chamber passed the law in a late-night session on Friday, after days of raucous debate in which legislators scuffled in committee meetings and an outnumbered opposition boycotted decisive votes. The lower house passed the bill under similar circumstances last month.

The uproar over the bill, which gives government agencies broad new powers to classify secrets and toughens penalties for officials who leak them, has eroded what had been unusually high support ratings for Mr Abe’s year-old administration.