A cyber gang with possible links to Russia is being blamed for the extraordinary worldwide computer security breach - possibly in retaliation for US airstrikes on Syria.

The mysterious organisation - called Shadow Brokers - claimed in April it had stolen a ‘cyber weapon’ from an American spying agency that gives unprecedented access to all computers using Microsoft Windows, the world’s most popular computer operating system.

The hacking tool had been developed by the National Security Agency (NSA), America’s powerful military intelligence unit. The NSA had developed its ‘Eternal Blue’ hacking weapon to gain access to computers used by terrorists and enemy states.

But in an astonishing twist, the NSA’s tool was stolen by Shadow Brokers.