But supporters of the treaty and the related British 2003 Act argue that the removal of the prima facie test simply means that suspects face the same broad test in each country.

BBC: US-UK extradition: The law explained

The 2003 Act effectively made it easier for the US to seek the extradition of someone from the UK because the US would no longer need to provide a "prima facie" case to British courts - proving your case on the face of available evidence.

BBC: US-UK extradition: The law explained

Requests should only be considered if the US authorities provide prima facie evidence that the suspect has a case to answer to prevent people being sent to face trial abroad on "speculative charges", it says.

BBC: Call for overhaul of UK extradition rules