A person on Twitter accused her of sending 'propaganda emails'
British Labour MP Yvette Cooper has said she has alerted police after receiving a death threat against her children and grandchildren.
The 'Remain' campaigner, who is married to former Labour shadow chancellor Ed Balls, received the tweet on Tuesday from an account that accused her of sending pro-EU "propaganda" by e-mail.
It said: "Hello, Yvette I have received your Stronger In propaganda emails 5 times please stop or I will kill your kids and grandkids".
Reposting the threatening tweet to her followers, Ms Cooper said: "Got this today for speaking out for Remain.....this has to stop."
She said both the police and Twitter were looking into the matter, adding: "But this is for all of us. Time to stop the hatred."
Got this today for speaking out for Remain..... This has to stop. pic.twitter.com/HPV8asrZ3w— Yvette Cooper (@YvetteCooperMP) June 21, 2016
It is understood the account has since been removed.
The incident comes amid an increase in security for MPs following the death of Ms Cooper's Labour colleague and fellow West Yorkshire MP Jo Cox.
The 41-year-old mother of two died after she was shot and stabbed in the street following a constituency surgery in Birstall, near Leeds, on Thursday last week.
The British National Police Chiefs Council said MPs were being reminded of the need to assess their personal security and of measures they might take to protect themselves.