Ian Norris, the British businessman who has been battling US efforts to extradite him for more than four years, is facing another protracted legal row over whether he can be sent to Pennsylvania to face obstruction of justice charges.

A London magistrates’ court ruled on Friday that while price-fixing charges against the former Morgan Crucible chief executive have been thrown out, he could still be extradited over allegations that he obstructed a US cartel investigation.