Labour's Tom Harris wants there to be a specific law forbidding "denial of service attacks" where floods of emails are used to wreck computer systems.

His 10-Minute Rule Bill, outlined in Parliament on Tuesday, would also increase jail terms for hackers.

The Home Office says it wants to revise existing laws and raise penalties.

Mr Harris told MPs the internet had changed beyond recognition since the current laws on hacking and spreading computer viruses were introduced in 1990.

"The media like to imagine that hacking, virus-proliferation and denial-of-service attacks using email are the product of bright but lonely, socially challenged teenagers sitting in their bedrooms," he said.

"This is an outdated, inaccurate and, I think, dangerous notion.

"Those who regularly and increasingly hold website operators to ransom are more likely to be members of an organised crime syndicate than the school computer club."

Networks hit

The Glasgow South MP said virus and worm attacks cost companies billions of pounds each year and should be taken seriously, with sentences to match.

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"The current levels of sentences do not reflect the seriousness of such offences," said Mr Harris.

He pointed to calls for sentencing reform after Exeter University student Joseph McElroy, who hacked into a US Government laboratory's computer network, was ordered to do 200 hours community service.

Mr Harris said "denial of service" attacks, where computer systems are deliberately overloaded with a flood of e-mails, had made some university networks unusable for hours at a time.

And an attempt to make the Manchester Police's computer system crash had involved sending thousands of threatening e-mails to the force's chief constable.

Government review

Mr Harris' bill would create a specific offence to tackle "denial of service" attacks - an issue which he says is at best ambiguous in the current laws.

It would also raise maximum sentences for hacking from six months to two years.

And possible jail terms for unauthorised modification of computer material from five to 10 years.

Mr Harris is due to meet Home Office Minister Paul Goggins soon to discuss the plans.

A Home Office spokeswoman said the government was considering raising the available sentences.

She said: "It is our intention to make some amendments to the Computer Misuse Act.

"These do include raising the penalty threshold of the section one offence [hacking] and the section 3 offence [unauthorised modification of material] and seeking to clarify the coverage of 'denial of service' attacks in the act."