SOMERTON and Frome MP Sarah Dyke is demanding a meeting with the Justice Secretary after the family of sisters killed by a speeding driver started a campaign to increase his sentence.

Thomas Lenthall, 40, must serve at least two-thirds of a 10-year prison stretch imposed by a judge in December.

But the family of Madison and Liberty North - known as Maddie and Libby - have blasted the jail term "a gross miscarriage of justice" as they believe it is too lenient.

A petition calling for Lenthall to serve a longer period behind bars has been started by the sisters' parents, Verity and Jason North, and has so far collected 41,902 signatures.

READ MORE: Speeding driver jailed following sisters' death.

Ms Dyke said: "The North family have suffered a devastating loss and it must be utterly heartbreaking for them that Maddie and Libby’s killer was not given a tougher sentence.

"I’ve written to the Secretary of State (Alex Chalk) urging him to meet me to discuss this case. Maddie and Libby deserve justice.”

Lenthall, of no fixed address, was driving at over 100mph when his car hit a vehicle in which Madison and Liberty, aged 21 and 17, were travelling on the A361 Frome Bypass on July 25 last year.

He pleaded guilty to causing their death by dangerous driving at Bristol Crown Court,