Britain's Attorney General Richard Hermer told officials in the Foreign Office that he cannot approve a decision to ban arms sales to Israel, without knowing if their use would breach international law, according to a report in The Guardian newspaper on Monday.
A ministry spokesperson said the British government must adhere to the law. He said the UK has been clear that it will not export weapons that could be used in its violation.
The spokesperson said there was an ongoing assessment ordered by the secretary, to determine whether Israel was in compliance with international law.
Foreign secretary David Lammy said he supported the sale of defensive arms to Israel so that it can continue to defend itself.
According to the guardian, exporters wishing to receive licenses to sell to Israel, have been stalled until a decision as to what arms would be barred from sale, is made.
The UK exports 18 million pounds of military equipment to Israel, annually, according to the Guardian. But officials in Jerusalem said they were worried that any suspension of sales would be a slippery slope.
The Labour government is unsure it would be able to defend any definition of defensive weapons in court. According to the report, UK Prime Minister Keir Starmer is participating in the deliberations.