Londoners are taking so much cocaine that the class A drug can be found in the Thames — and it is being taken throughout the week, not just at weekends, according to scientists.

It is feared that the high level of cocaine is hurting the river’s wildlife, with separate research showing that it makes eels hyperactive.

Researchers used a monitoring station near the Houses of Parliament to assess how rising cocaine use, plus downpours that overwhelm waste plants and carry sewage into the river, were damaging it. The cocaine comes from users’ urine and can be detected in wastewater but should be removed by water treatment and dilution. In the Thames, however, that system is failing, with a constant low level of cocaine that surges