By Agence France-Presse
Robert Dawes, 46, believed to have been one of Europe's biggest drug traffickers, is alleged to have flown the drugs into France from Caracas, Venezuela, in 2013 in 30 unregistered suitcases aboard an Air France plane.
British police officer Robert Hickinbottom, giving evidence by video link from to the special French court composed only of judges, said Dawes operated "at the top international level".
He said Dawes was suspected of involvement in the 2002 murder of a teacher in the Netherlands, money-laundering operations in the United Arab Emirates and Switzerland and dealings with Colombian drug cartels.
Hickinbottom who works for the National Crime Agency (NCA), Britain's organised crime unit, said he had been tracking Dawes' criminal path for years.
Dawes was arrested in November 2015 at his home in southern Spain and extradited to France.
He is on trial alongside two other Britons and three Italians, who risk up to 30 years in prison and fines of up to 7.5 million euros ($8.5 million) if convicted.
The Air France shipment caused outrage in Venezuela where the interior minister admitted the suitcases had gone through security scanners that had clearly showed the presence of drugs.
Venezuelan police arrested 25 people, including members of the military and an Air France manager.
Dawes is due to testify on Tuesday with a verdict expected on December 21.