LONDON • A hacking group calling itself the "Shadow Brokers" and with possible links to Russia is being blamed for the unprecedented wave of cyber attacks that swept across the world on Friday.

Last month, it claimed to have stolen a "cyber weapon" from a US spy agency that gives unprecedented access to all computers using Microsoft Windows, the world's most popular operating system.

The hacking tool - "Eternal Blue" - was developed by the National Security Agency and used to gain access to the computers of terrorists and enemy states. The hackers, who have not come forward to claim responsibility or otherwise been identified, "dumped" the computer bug on an obscure website on April 14. This took place just a week after US President Donald Trump ordered the bombing of Syria, The Telegraph reported.

Some experts believe the timing is significant and indicates that the group has links to the Russian government, the British newspaper added.

In an Internet posting on April 8, a day after the first air strikes, the group appeared to issue a warning to Mr Trump.

In a statement, it said in broken English: "Respectfully, what the f*** are you doing? The Shadow Brokers voted for you. The Shadow Brokers supports you. The Shadow Brokers is losing faith in you. Mr Trump helping the Shadow Brokers, helping you. Is appearing you are abandoning 'your base', 'the movement', and the peoples who getting you elected."

Nobody knows who is behind the group but in a statement to a specialist technology website last December, it said: "The Shadow Brokers is not being irresponsible criminals. The Shadow Brokers is opportunists. The Shadow Brokers is giving 'responsible parties' opportunity to making things right."