School computer networks blocked more than 2000 online threats every minute when students returned to school after the first Covid-19 lockdown last year.
The schools' Government-funded Network for Learning (N4L) says it blocked 120 million cyber security threats to schools during term two last year, 14 per cent more than in term one.
They included a spike in "distributed denial of service" attacks, where a flood of internet traffic attempts to overwhelm a website, in the week of May 24 shortly after schools reopened for all students after the national lockdown.
The numbers are massive because of many automated systems which attempt to update repeatedly, but include a small minority of cases where students tried to access material such as games and pornography which are blocked by the network.
Blocks of gaming sites doubled in primary schools between the first and second terms, and rose by 24 per cent in secondary schools, rising to 20 per cent of all blocks made by the network - second only to blocks of file-sharing and storage sites, which made up 21 per cent of all blocks.