Boris Johnson is facing another showdown with rebel Tory MPs on China and genocide after the House of Lords triggered a further Commons vote on the issue.
Amid accusations of “dirty tricks” by ministers, 33 Conservative peers voted against the government as the Lords inflicted a defeat by 367 votes to 214, a majority of 153.
The rebel peers included former senior cabinet figures Eric Pickles, John Gummer, Sayeeda Warsi and Michael Forsyth, and ex-ministers David Maclean, Ros Altmann, Nicola Blackwood and Angela Browning.
The vote was on a proposal for a parliamentary panel of judicial experts to rule on whether countries signing post-Brexit trade deals with the UK have carried out acts of genocide.
The stakes have been dramatically raised by allegations regarding China‘s brutal treatment of the Uighur people in its Xinjiang province, where thousands of people are said to be living in concentration camps.
There have been reports of sterilisation of women and the forced removal of children from their families, although China denies there is abuse of the Uighur minority Muslim population.
Two weeks ago, amid heated scenes in the Commons, 31 Conservative MPs voted against the government as the prime minister avoided defeat on an amendment to its Trade Bill by just 15 votes.
The anger was over a government move not to allow MPs a vote on a Lords amendment giving powers to the High Court to block a trade deal with a country guilty of genocide.
Instead, the government put forward an amendment by Tory MP Sir Bob Neill giving select committee chairs a say over trade deals with countries with poor human rights records.
The new amendment passed by the Lords, proposed by the former Liberal Democrat MP Lord Alton, gives the power to rule on genocide to a parliamentary panel of judicial experts instead of select committee chairs.
And in a process known as parliamentary “ping-pong”, the bill now returns to the Commons, where the government faces another Tory revolt which opposition peers claim could be big enough to defeat the government this time.
Launching his latest bid to strengthen the bill, Lord Alton told peers: “We have failed to predict genocide, we have failed to prevent genocide, we have failed to protect victims of genocide and we have failed to prosecute perpetrators of genocide.
“The genocide amendment is a modest attempt to begin to address some of those failings.”
He added: “We have tweaked the government amendment, which would enable the appropriate select committee to refer evidence, if they have found some, to an ad hoc judicial committee comprised of members of our House who have served at the highest levels of the judiciary.
“Although emphatically it is not a court, which was the preferred option of peers, it would be empowered to determine whether the evidence is sufficient to support the claim that genocide has been or was being committed by a state counter-party to a bilateral trade agreement.”
Lord Alton warned: “Parliament must not allow itself to become part of an alibi for inaction.”
But government minister Lord Grimstone told peers: “The establishment of an ad hoc parliamentary judicial committee would represent a fundamental constitutional reform.
“It would blur the distinction between courts and parliament and upset the constitutional separation of powers.”
He said: “Ultimately, the question of how we respond to concerns of genocide as it relates to our trade policy is a political question.”
During the debate, one of the Tory rebels, former MP Lord Patrick Cormack accused the government of offering “fig leaves” to the Lords and urged peers to back Lord Alton’s “sensible, realistic and balanced” amendment.
And Lord Blencathra, who as Mr Maclean was Tory chief whip in the Commons, said MPs had been robbed of a chance to vote on Lord Alton’s previous proposal by the government’s “dirty under-handed trick”.
He dismissed the government’s case as a “sham” and said ministers were terrified of offending the Chinese regime.
It was time for the Western world to “get off its knees and start to stand up to China before it is too late”, he added.