Tech firms such as Google, Facebook or Twitter have an “ethical responsibility” to stop terrorists using the internet to plot attacks and purchase bomb materials, according to the head of MI5.

In a somewhat rare public appearance yesterday, Andrew Parker, the director-general of the Security Service in the UK, said terrorists were taking advantage of the quickening pace of technology to plan deadly attacks in days.

Parker went on to note the country was facing an “intense” threat from Islamist extremists, which was at the “highest tempo” in 30 years.

Additionally, the security chief said citizens had a “reasonable expectation” that firms would do whatever they could to help tackle the issue.

As part of his speech in London, Parker said: “No company wants to provide terrorists with explosive precursors, social media platforms don’t want to host bomb making videos and communications providers don’t want to provide the means of terrorists planning beyond the sight of MI5. Some helpful action is being taken but there is a challenge of pace, volume and reach as these technologies continue to develop so rapidly.”

Parker highlighted that the Islamist threat was operating at an unprecedented scale, noting there had been a “dramatic” rise in terror plots, which had become increasingly difficult to detect. These, he added, would usually be carried out in just a matter of days.

“The threat is more diverse than I’ve ever known. Plots developed here in the UK, but plots directed from overseas as well. Plots online. Complex scheming and also crude stabbings; lengthy planning but also spontaneous attacks. Extremists of all ages, gender and backgrounds, united only by the toxic ideology of violent victory that drives them. These threats are sometimes now coming at us more quickly,” he added, noting that despite his calls for tech firms to do more, he was not trying to hold back the tide of developing technology.

Parker’s remarks come after a string of terrorist attacks in Manchester and London, which resulted in the deaths of 35 people, and follow on from other calls for tech giants to combat online extremism.

Just last month the UK PM urged technology giants to go “further and faster” to stop the propagation of online terrorist material – including the creation of new technologies to ensure it stopped appearing online in the first place.