London is the cocaine capital of Europe - but only during the week, new analysis suggests.

When use of the Class A substance on weekends is also taken into account the city has been overtaken for the first time in three years.

The findings emerged in a study of drug concentrations in sewage in dozens of European cities across 18 countries.

Tests conducted in March showed the average weekday concentration of cocaine in London's wastewater was 949.3mg per 1,000 people per day.