Newcastle University has already produced a human-animal embryo
Christian campaigners have lost their High Court challenge to scientists being allowed to create human-animal embryos for research purposes.
The Christian Legal Centre and Comment on Reproductive Ethics were refused permission to bring a test case application for judicial review.
They had wanted to overturn a decision of the research regulator the Human Fertilisation and Embryology Authority.
But the judge ruled their challenge was unarguable.
Mrs Justice Dobbs, sitting at the High Court in London, ruled that the application was "totally without merit".
The Christian Legal Centre (CLC) and Comment on Reproductive Ethics had claimed the HFEA had operated unfairly in permitting the work.
But the HFEA said all decisions were made in a transparent way that followed correct procedures.
The challenge was against an HFEA ruling earlier this year to grant licences to scientists at Newcastle University and King's College London in January. A third team in Warwick has subsequently been granted a licence as well.
Supporters of inter-species research say their work could one day help treat or even cure patients with serious medical conditions.
But Josephine Quintavalle, spokeswoman for Core and a named party in the action, said the regulator was "too pro-embryo research" and did not give opponents enough of a voice in the decision-making process.
"The way the regulator works is not fair. No-one representing the interests of the embryo can sit on the committees that make decisions and once a decision has been reached we cannot appeal it."
She also said the HFEA acted outside its jurisdiction - at the time of the January verdict a bill was still in the process of being drawn up covering this very issue.
That bill has now been passed and will come into force next year allowing such applications to be considered.
The HFEA has always maintained it was right to consider the original application as the 1990 law it was working under stipulated the regulator was able to interpret guidance as science progressed so as not to slow down research.
A spokeswoman said: "The HFEA is pleased with the court's decision. We always believed that we acted lawfully and responsibly when considering these research licence applications."
Andrea Minichiello Williams, spokeswoman for CLC, said: "This is a sad day for justice in this country."
The CLC now faces a legal bill for £20,000.