Anas Sarwar, the Scottish Labour leader, has become the latest senior party figure to urge an immediate ban on UK arms sales to Israel, as ministers face pressure to disclose the government’s official legal advice on the trade. Sarwar told BBC Scotland that Israel had “clearly” breached international law in Gaza and that UK arms sales should be halted immediately. On Thursday Sadiq Khan, the London mayor and the party’s other senior Muslim figure, made the same call. Labour’s official policy is to await information on the legal advice provided to ministers and to only push for an end to arms sales if this says continued weapons sales could risk the UK breaching international law. In March, David Cameron, the foreign secretary, said information about the advice would be published within days, but ministers have since backtracked and are refusing to say if and when this might happen. Whitehall sources say the issue is complicated by the fact that the legal advice is understood to be nuanced, and that it is based on an evolving situation, meaning it could be toughened up following incidents such as the killing of seven aid workers in Israeli drone strikes on Monday. “This advice has been batted around for a while but it’s a complex, moving thing,” one Whitehall source said. “As well as the legal implications, they also need to balance diplomatic considerations and what other allies might do.” But with Lord Cameron refusing to engage with questions on Gaza during media engagements at the Nato summit in Brussels on Thursday, there is increasing pressure on the Foreign Office and Downing Street to make a decision, amid increasing misgivings among some officials involved in the process. Dave Penman, the general secretary of the FDA union, which represents senior civil servants, said that while any moral objections among officials were not relevant to their work, the fact that a large number of senior judges and others had warned that continued arms sales could break international law was different. “Civil servants have their own legal obligations under the civil service code to uphold the rule of law,” he told LBC radio. “So I think we’re in the grounds of where this is a legitimate question to be asked, and the government really need to settle it. They need to get on with this. What everyone needs to know is: what is the settled government legal view on the legal position?” Alicia Kearns, the Conservative MP who chairs the foreign affairs select committee, added her voice on Friday to a growing number of Tories calling for action. “I believe we have no choice but to suspend arms sales and it is important that the public understands this is not a political decision as some people want to present it as,” she BBC Radio 4’s Today programme. “Legal advice is advisory so the government can choose to reject it but UK arms export licences require a recipient to comply with international humanitarian law. That is why emergency handbrakes exist in terms of change of circumstances.” Some reports have talked of potential cabinet splits over a possible ban on continued arms sales, highlighting potentially different views between Cameron and more pro-Israel ministers such a Kemi Badenoch, the business secretary, who has to sign off arms export licenses. Some government sources have discounted a split, even though Cameron and his department are generally seen as more likely to push for any action against Israel.