People who seek out and read radical Islamist publications online could face prosecution, the Metropolitan Police has warned.
The caution comes after an online radical al Qaeda-linked magazine, Inspire, incited its readers to attack public targets in the West.
The Met also issued a formal advisory to other police forces following the publication of the latest issue of the banned title.
A spokesman for the force said: "The MPS counter terrorism command is aware of the websites and appropriate steps have been put in place, including providing security advice where relevant.
"The public is reminded that viewing downloading or disseminating extremist material within the UK may constitute an offence under Section 1 and 2 of the Terrorism Act 2006.
"As part of our continued work, we regularly work with, and support, industry, the organisers of sporting events and companies overseeing crowded places with a variety of briefings and advice."