A scientist in China who said he had created the world's first gene-edited babies has been jailed for three years.

He Jiankui was convicted of violating a government ban by carrying out his own experiments on human embryos, to try to give them protection against HIV.

He was globally condemned when he announced his experiments, and the birth of twin babies, last November.

Xinhua news agency said a third baby was also born at the same time, which had not previously been confirmed.

The local government in Guangdong province said it was keeping the babies under medical observation.

As well as the prison sentence, He was fined three million yuan ($430,000; £328,000).

The court also handed lower sentences to two men, Zhang Renli and Qin Jinzhou, for conspiring with He to carry out the experiments.

A court in Shenzhen said the men had acted "in the pursuit of personal fame and gain", and had seriously "disrupted medical order", Xinhua news agency reported.

"They've crossed the bottom line of ethics in scientific research and medical ethics," the court added.

What happened last year?

He announced the birth of gene-edited twins called Lula and Nana in a video, filmed by Associated Press, in November 2018.

Describing his experiments, He said: "I understand my work will be controversial - but I believe families need this technology and I'm willing to take the criticism for them."

After the video was released, the backlash from the science community both in China and around the world was swift and forceful.

The Chinese government placed He under police investigation and ordered his research work be stopped.

He was also fired by the university where he was an associate professor, the Southern University of Science and Technology in Shenzhen.

The Chinese Academy of Science released a statement about He, saying it "firmly opposed" gene editing on humans.

"Under current circumstances, gene editing in human embryos still involves various unresolved technical issues, might lead to unforeseen risks, and violates the consensus of the international scientific community," the statement added.

Research later showed that He may have given the babies a mutation that significantly shortens their life expectancy.

How did the experiment work?

He was targeting a gene called CCR5.

This is a set of genetic instructions that are important for a functioning immune system - but they are also the doorway that human immunodeficiency virus (HIV) walks through to infect cells.

Mutations to CCR5 essentially lock the door and give people resistance to HIV.

According to South China Morning Post, He recruited seven heterosexual couples who wanted children to take part in the study. The men were all living with HIV, while the women were not.

The professor made embryos in an IVF clinic, and used gene-editing technology known as CRISPR-Cas9 to change the CCR5 gene.

He then forged documents in order to pass a mandatory ethics review, and fabricated information so that medical doctors would unknowingly implant the gene-edited embryos into two women.

What are the repercussions?

The full consequences of gene-editing babies are unclear, but the effects could be permanent.

If the babies grow up to have children of their own, any genetic modifications could be passed down through the generations. This could potentially introduce a lasting change to the human race.

This is even more complicated in the case of He's experiment.

Earlier this month, when He's original research was published for the first time, scientists said the results did not show what He had said they did.

While He had targeted the correct gene, they said, he had not created the exact mutation associated with resistance to HIV.

Instead, He created previously-unseen genetic edits - the effects of which are currently unknown.

Prof Robin Lovell-Badge, from the UK-based Francis Crick Institute, told BBC News that they "just can't tell" what the effects of these edits will be.

"There have never been any studies on these specific mutations because they haven't existed before," he said.

"He was very foolish. He thought he knew better, but the techniques are just not there yet to do [genome editing] safely and efficiently."

The long-term effects remain to be seen - but, Prof Lovell-Badge added, the main concern is "whether the three babies born are going to be healthy and looked after well".