City of London Police were asked to work with the Food Standards Agency (FSA) as part of its inquiry into the scandal. It reviewed evidence from law enforcement agencies in Europe and the UK, as well as from the FSA.
The force launched an investigation in May and said it made the arrests "during the initial stages" of the inquiry. Officers also carried out searches at businesses and homes in the UK.
Detective Chief Superintendent Oliver Shaw, from the City of London Police, said:
This is an extremely complex investigation covering a number of jurisdictions and a variety of businesses.
We are working closely with police forces, other law enforcement agencies and regulators to determine whether horsemeat being used in a range of meat products was deliberate and coordinated criminal activity.
More top news
William and Kate will visit the country between October 14 and 18.
The teenager was killed when his motorbike crashed into a car allegedly driven by an American diplomat’s wife.
The alleged incident took place on Saturday afternoon.