Nine people have been jailed in China for smuggling fentanyl into the US, after a landmark joint investigation by American and Chinese officers.

In August, US President Donald Trump said China was not doing enough to stop the opioid – 50 times more potent than heroin – being shipped to the US.

The Chinese court said it was the first time US and Chinese officers had worked together on such a case.

Mr Trump has claimed fentanyl kills “100,000 Americans a year”.

According to US authorities, the figure is likely to be lower. The Centers for Disease Control and Prevention said in 2017 – the most recent full data available – that synthetic opioids, other than methadone, were linked to 28,000 deaths.