A botnet called Necurs which is believed to be made up of around six million infected Windows machines has gone quiet according to internet security firms.

Necurs has been used to send junk mail and malware from various cyber-thieves but in recent months has appeared to slow down.

The first signs of this was the reduction of infected emails spreading the banking Trojan named Dridex and the ransomware program named Locky.

Experts believe that some of Necurs administration systems have disappeared and that is maybe looking for a new command and control system to feed it instructions.