Freed anti-fracking activists greeted by supporters as they leave Preston Prison

Simon Blevins, Richard Roberts and Rich Loizou were jailed at Preston Crown Court in September after being found guilty of public nuisance over a protest last July at Cuadrilla's fracking site in Lancashire.

But they were freed on Wednesday by Court of Appeal judges, who said their original sentences were "manifestly excessive".

They were greeted by more than 30 supporters, as well as a number of camera crews and journalists, as they left HMP Preston shortly after 4pm.

Giving a statement on behalf of all three outside the prison, Loizou said: "Today's decision affirmed that when people peacefully break the law out of a moral obligation to prevent the expansion of fossil fuel industries they should not be sent to prison.

"The fracking industry threatens to industrialise our beautiful countryside.

"It will force famine, flooding and many other disasters on the world's most vulnerable communities by exacerbating climate change.

"Fracking is beginning right now so there has never been a more critical time to take action.

"The planet needs you."

He urged people to join the trio at a mass demonstration on Saturday outside the Preston New Road site, in Little Plumpton.

Two mounted police officers were also outside the prison as supporters gathered.

Earlier on Wednesday lawyers for the men, known by supporters as the Frack Free Three, said they may challenge their convictions on the basis of "apparent bias" by the crown court judge.

The three climbed on to lorries outside the energy firm's site in a stand-off which lasted almost 100 hours.

Soil scientist Blevins, 26, from Sheffield, and teacher Roberts, 36, of London, were both jailed for 16 months, while piano restorer Loizou, 32, from Devon, was given 15 months after being convicted of public nuisance.

But the Lord Chief Justice Lord Burnett said the sentences were "manifestly excessive" and replaced them with conditional discharges.

Supporters in the packed courtroom, who had gathered outside for a demonstration before the hearing, erupted into applause as the decision was announced.

The men were the first environmental protesters to be imprisoned since the Kinder Scout mass trespass of 1932.

In her submissions to the court, Kirsty Brimelow QC, for the protesters, said they were involved in a "peaceful protest" and that all three have "acted and lived in a way that is entirely selfless".

She told the court the sentences had a "chilling effect" on protest.

At the sentencing hearing on September 26, Judge Robert Altham said he could not suspend the jail terms despite accepting the impact of incarceration and the good they did in the community.

Speaking outside court after the ruling, Ms Brimelow said the men's legal teams will now consider whether to challenge their convictions on the basis of the "apparent bias" of the judge.

She told the court during the hearing Judge Altham's sister had written a letter in support of fracking in 2015.

A spokesman for the Judicial Conduct Investigations Office confirmed it has received a complaint about Judge Altham, which it will consider.

The protesters' appeal was supported by human rights organisation Liberty and environmental campaign group Friends of the Earth.

A fourth activist, Julian Brock, 47, from Torquay, was sentenced to 12 months in custody, suspended for 18 months, after he admitted public nuisance.

Mr Brock did not challenge his sentence.

Last week Cuadrilla was given the go-ahead to start work at the site following a failed High Court bid by campaigners to block fracking due to safety concerns.

Lord Burnett said the court will give full reasons for its decision at a later date.