Labour's Gordon Brown has paid tribute to Jo Cox describing her as "the most vivacious, personable, dynamic and committed friend you could ever have".
He said that he and his wife Sarah worked with Ms Cox and her husband Brendan working with families in poverty.
Brown added that she had visited some of the most dangerous places in the world, adding: "The last place she should have been in danger was in her home town."
The 41-year-old Labour MP died after she was shot on the street in Birstall, West Yorkshire outside a library where she held regular surgeries in her constituency.
Our memories will be for ever scarred by this moment. Our hearts will always be hurt at our country’s loss.
Sarah Brown also released a statement saying she is "heartbroken" and describing Ms Cox as having a "truly remarkable spirit and passion ".
I am heartbroken. Jo had a truly remarkable spirit and passion that shone through in her work with Oxfam and with me on our countless campaigns for women and children.