Two more people have been arrested over abuse sent to Labour deputy leader Angela Rayner.
A 65-year-old man from Surrey and a 37-year-old man from Kent are accused of malicious communications over an email sent to the Ashton-under-Lyne MP on May 2 this year.
Greater Manchester Police (GMP) said both men have been released under investigation pending further inquiries.
The latest arrests take the total number of people detained under so-called Operation Octant, the investigation into abuse and threats aimed at Ms Rayner, to eight.
GMP won’t tolerate abuse, and that includes online abuse in its many forms – text, email or social media— DS Christopher Dean, Greater Manchester Police
Detective Sergeant Christopher Dean, from GMP, said: “GMP won’t tolerate abuse, and that includes online abuse in its many forms – text, email or social media – and we will always investigate thoroughly to bring the perpetrators to justice.
“If anyone has been the victim of abuse – whether physical or online – then they should call police and one of our specially-trained officers will be on hand.”
Anyone with information about similar incidents can contact police on 0161 856 9262, via 101, or the LiveChat function at www.gmp.police.uk. To remain anonymous contact Crimestoppers on 0800 555 111 or online.
