Terrorist attacks across three continents last Friday demonstrate the influence of Islamic State and wide reach, as well as the difficulties of countering its use of the internet to galvanise and inspire global violence.

US intelligence agencies added the mother of the Boston bombing suspects to a government terrorism database 18 months before the bombings, two officials said.

A prominent Nigerian banker was today meeting security officials over fears his son may have been the man who allegedly tried to bomb a US-bound flight.