Image copyright Reuters Image caption Sister Megan Rice (middle) and fellow activists Greg Boertje-Obed (left) and Michael Walli

A US federal appeals court has ordered the immediate release of three anti-nuclear activists, including an elderly Catholic nun, the group's lawyer says.

Attorney Bill Quigley says he hopes they will be released within days.

Last week, sabotage convictions against Sister Megan Rice, 85, Michael Walli, 66, and Greg Boertje-Obed, 59, for breaking into a Tennessee nuclear facility in 2012 were overturned.

But it upheld guilty verdicts for damaging government property.

Sister Megan was jailed for nearly three years for entering the Oak Ridge facility, which stores uranium.

The other two protesters were each sentenced to more than five years in prison.

The July 2012 incident prompted security changes at the Y-12 site.

'Displays of ineptitude'

On Friday, Mr Quigley said he was trying to get the three activists out of prison as soon as possible.

They have spent two years behind the bars, and the appeals court said they likely already had served more time than they would received for the lesser charge.

The campaigners are members of the group Transform Now Plowshares.

During their trial last year, Walli and Boertje-Obed received tougher sentences because they had longer criminal histories.

The trio were also found guilty of causing more than $1,000-worth (£650) of damage to government property.

After cutting a fence to enter the site, they walked around, spray-painted graffiti, strung out crime-scene tape and chipped a wall with hammers.

They spent two hours inside the site.

The trio also sprayed the exterior of the complex with baby bottles containing human blood.

When a guard approached, they offered him food and started singing.

At the trial, Sister Megan said her only regret was waiting so long to stage her protest. "It is manufacturing that which can only cause death," she said.

US lawmakers and the Department of Energy later launched an inquiry and uncovered "troubling displays of ineptitude" at the facility.

Top officials were reassigned, including at the National Nuclear Security Administration.

WSI, the company providing security at the site, was dismissed and other officers were sacked, demoted or suspended.