LONDON (AP) — A new U.K. parliamentary report is demanding that social media companies do more to tackle sites that promote extremism.

The Home Office Committee report says Google, Facebook and Twitter are leaving cyberspace "ungoverned and lawless," making it possible for the forums to be the lifeblood of Islamic State.

Committee chairman Keith Vaz says huge corporations "with their billion-dollar incomes, are consciously failing to tackle this threat and passing the buck by hiding behind their supranational legal status, despite knowing that their sites are being used by the instigators of terror."

Despite their size, Vaz says the companies deploy only a "few hundred" employees to monitor billions of accounts.

But Peter Neumann, a professor at King's College London who studies radicalization, said Thursday that blaming the internet alone is too simplistic.