Ministers have been accused of making a “mockery of democracy” by blocking a clear vote on giving the UK courts a role in determining whether a genocide is taking place. The issue, wrapped up in the trade bill, will now return to the Lords where the proposal for a role for the UK courts – driven by allegations that Uighur Muslims are suffering a genocide at the hands of the Chinese government – is likely to be inserted for a third time. Ministers had arranged Tuesday’s vote so that if Tory rebels backed an amendment passed by the Lords giving UK courts a role, they would also be backing a separate Labour-sponsored amendment imposing human rights audits before trade deals are signed. Some Tory MPs were prepared to rebel to give the courts a role, but not if by so doing they would also be backing the Labour-sponsored plan. The independent peer Lord Alton said after the vote: “I am this evening preparing to retable the genocide amendment to enable the elected house to have the opportunity to vote on a fundamental issue. Denying them that right makes a mockery of democracy.” There is a significant majority in the Lords for giving the courts a role in determining genocide. If peers reinsert the proposal, Tory rebel MPs, in alliance with opposition parties, have promised to try to ensure a clean vote on the issue when it returns to the Commons, probably next week. In the only boost for ministers, MPs passed by 318 to 303 a government-sponsored compromise giving the foreign affairs select committee a role to investigate genocide and make recommendations in a Commons debate. Most MPs on the foreign affairs select committee regarded the offer as worthless, with one member, Chris Bryant, describing it as “the worst piece of parliamentary jiggery pokery” he had seen in 20 years. The Labour MP added: “The bottom line is that this government seems to want to do everything in its power to prevent us as a nation clearly and unambiguously standing up against human rights abuse in China.” He said ministers had blocked a vote knowing they would lose. Ministers used their control of the Commons order paper to prevent a clean vote on a Lords amendment to give the high court a role in advising parliament if a country with which the UK may negotiate a trade deal is committing genocide. Instead ministers welded two separate issues – the Labour proposal for human rights audits of trade agreements and the proposed role for the UK courts in genocide – into a single vote on the order paper. The trade minister Greg Hands said it was a longstanding convention for related Lords amendments to be packaged together, but Tory MPs accused him of underhand tactics that were beneath him. Sir Iain Duncan Smith said: “The government’s attempts to deny MPs a vote on the genocide amendment are cynical to the extreme. Now is not the time for parliamentary games. Members from across the house have voiced their support for this amendment and they must be heard.” The episode has revealed nervousness in the executive about the triple threat of losing control of its China policy, extending ministerial accountability to parliament for its trade policy and providing a novel UK judicial route to determine if foreign powers are committing genocide. Ministers also appear to have been caught off guard by the power of a campaign largely built up outside parliament demanding tougher action to protect Uighur Muslims. The alliance spans religious groups, victims of genocide, human rights campaigners and international lawyers. Thirty-three Tory MPs rebelled the last time they were given a straight vote on a role for the courts to rule on genocide, cutting the overall Commons majority to 11. The scale of the whipping led to a backlash and claims that the then chief whip, Mark Spencer, considered his job to be on the line with the vote.