Young men and boys fuelled by “strongly misogynistic” online material are hunting for vulnerable women and girls to exploit on websites such as eating disorder and suicide forums, senior officers have said.

The threat from young males wanting to carry out serious harm is so serious that counter-terrorism officers are joining the National Crime Agency (NCA) in the hunt for them, fearing they could go on to attack or kill.

Britain’s head of counter-terrorism, Matt Jukes, told the Guardian that a joint taskforce would be set up between his force and the NCA to tackle those fixated with violence online, in what he called a “decisive moment”.

Jukes, the Metropolitan police force’s assistant commissioner for specialist operations, said the new pairing would look for those consuming online material about killings or sexual abuse. Those who might go on to plot school shootings and other mass attacks, as well as those who encouraged women and girls to harm themselves, would also fall under their remit.