Internet trolls could face up to two years in jail under new laws, Justice Secretary Chris Grayling has said.
He told the Mail on Sunday quadrupling the current maximum six-month term showed his determination to "take a stand against a baying cyber-mob".
Mr Grayling was speaking days after TV presenter Chloe Madeley suffered online abuse, which Mr Grayling described as "crude and degrading".
She has welcomed the proposed laws but said social media should be regulated.
Social media 'venom'
Under the measures, magistrates could pass serious cases on to crown courts.
The law change is to be made as an amendment to the Criminal Justice and Courts Bill going through Parliament, and due to be debated in the House of Lords in the coming week. The Bill applies to England and Wales only.
The new measures would also give police more time to collect enough evidence to enable successful prosecutions to be brought.
Mr Grayling told the newspaper: "These internet trolls are cowards who are poisoning our national life.
"No-one would permit such venom in person, so there should be no place for it on social media. That is why we are determined to quadruple the current six-month sentence."
Miss Madeley received threats after defending her mother Judy Finnigan's comments on a **** committed by footballer Ched Evans, which she said was "non-violent" and did not cause "bodily harm".
Richard Madeley has said "prosecution awaits" those who sent "sick **** threats" to his daughter.
The justice secretary said: "As the terrible case of Chloe Madeley showed last week, people are being abused online in the most crude and degrading fashion.
"This is a law to combat cruelty - and marks our determination to take a stand against a baying cyber-mob.
"We must send out a clear message - if you troll you risk being behind bars for two years."
Miss Madeley said she was an "avid supporter of free speech and of social networking".
"However, threats of any kind must not be interpreted as freedom of speech. Threatening to harm others is extreme and crosses the line of personal opinion into criminal behaviour.
"I am pleased the government are now talking about ways to deter trolls, and quadrupling the sentencing is a good place to start."
She added that the Malicious Communications Act is 10 years old and outdated, having been drawn up before Facebook and Twitter gained prominence.
"While I agree that spending time and money on trolls is somewhat disagreeable, social networking has become the most influential and powerful voice of the people, and the fact of the matter is it now needs to be regulated."
Claire Hardaker, an academic from Lancaster University who studies online aggression, said proving the intent of a threat on the internet was difficult for police.
"It's like your mum sending you a text saying 'I'm going to kill you' because maybe you forgot to bring something that she asked you to bring, versus somebody on the internet saying 'I'm going to kill you'," she said.
"You have to know the intent of the two different people and to know the intent of the stranger on the internet you've got to be able to read their mind.
"Proving intent, proving that they really meant it, that they had the means to carry it out, it's very difficult."
Former Conservative MP Edwina Currie, who has experienced online abuse, said people should learn to show restraint when making online comments.
"Most people know the difference between saying something nice and saying something nasty, saying something to support, which is wonderful when you get that on Twitter, and saying something to wound which is very cruel and very offensive.
"Most people know the difference - I don't think education is the issue. I think making sure society takes a dim view of the latter is exactly the right thing to do."
Labour MP Stella Creasy, who has been the target of Twitter trolls, says police and prosecutors need better training on stalking and harassment to deal with online abuse.
"We need the police and the CPS to have better training in what stalking is and what harassment is to understand that if somebody is sending messages and escalating their fixation on somebody... to be able to assess the risk the person faces," she said.
"It's no good saying we'll extend sentences if we're still reaching that barrier where people say, 'Well someone sent you a message online, don't be offended by it'."
Peter Nunn, 33, from Bristol, sent abusive Twitter messages to Ms Creasy after she campaigned to put Jane Austen on the £10 note. He was jailed for 18 weeks earlier this year.
Those who subject others to sexually offensive, verbally abusive or threatening material online are currently prosecuted in magistrates' courts under the Malicious Communications Act, with a maximum prison sentence of six months.
Under the act, which does not apply to Scotland, it is an offence to send another person a letter or electronic communication that contains an indecent or grossly offensive message, a threat or information which is false and known or believed by the sender to be false.
More serious cases could go to crown court under the new proposals, where the maximum sentence would be extended.
Mr Grayling announced earlier this month that the bill would also have an amendment dealing with so-called "revenge porn", with those posting such images on the internet facing two years in jail.