Female MPs from all parties were sent more than 25,000 abusive messages on Twitter in just six months this year, research by Amnesty International has found.

The charity accused the social-media website of failing to take down rape threats and death threats and warned they are having a "chilling effect" and could drive women off the internet completely.

It found that nearly half of all abusive messages were directed at Diane Abbott, the shadow home secretary, including racist Tweets and death threats.

Ms Abbott told Amnesty: " My office got flooded with communications, both by letter and by email. People sent us emails and letters full of swastikas, people sent us postcards and letters with pictures of monkeys and chimps.

“People sent us hundreds of emails using the word n***** - that’s the sort of response we get. It’s highly racialised and it’s also gendered because people talk about rape and they talk about my physical appearance in a way they wouldn’t talk about a man.”