A man has been arrested on suspicion of making threats to kill in an email to Labour Party leadership contender Angela Eagle.
Merseyside Police said a 44-year-old suspect is being questioned following an arrest in Paisley, Renfrewshire, on Friday.
A police spokeswoman said: “A 44-year-old man has been arrested on suspicion of making threats to kill.
“Officers from Merseyside Police executed a warrant in Paisley, Scotland, this morning, Friday July 15, and arrested the man.
“He will be questioned by Merseyside detectives today.
“The arrest comes after an email was sent to the account of Wallasey MP Angela Eagle.”
On Tuesday, it emerged a brick was thrown through the window of Ms Eagle’s constituency party office – a day after she announced her leadership challenge to Jeremy Corbyn.
Following the incident, Paul Stuart, co-vice chairman of the Wallasey Constituency Labour Party (CLP), said it was not an isolated incident and that Ms Eagle had been on the receiving end of a series of “really vile” homophobic emails and telephone calls.
Merseyside police and crime commissioner Jane Kennedy said members of the “hard left” were creating a climate which encouraged such attacks and said the building – which also houses other businesses – would be given “special attention” by police.
In response to the criminal damage, Ms Eagle said Mr Corbyn needed to “get control” of his supporters.
Mr Corbyn went on to issue a statement calling for calm and urging party members to treat each other with “respect and dignity”.