Attorney general intervenes in Foreign Office review of weapons sales to Israel

Exclusive: Richard Hermer tells officials he can't approve decision to ban arms without knowing if their use would breach international law

Keir Starmer's most senior legal adviser has intervened in the contentious decision over whether to ban UK arms sales to Israel, the Guardian has learned, as officials struggle to distinguish between offensive" and defensive" weapons.

Sources say Richard Hermer, the attorney general, has told Foreign Office officials he will not approve a decision to ban some weapons sales until they can say for sure which could be used to break international humanitarian law.