Two murderers slashed another convicted killer in an attack at one of Scotland's toughest jails.

Daryl Brady and Darren Smith pounced on Sean Kergan in the exercise yard of HMP Shotts last May.

Kergan was left scarred for life after being struck with blades melted on to plastic cutlery from the prison.

A judge heard how there had been “bad blood” between Brady and Kergan amid claims of an earlier assault.

Despite the animosity, prison bosses moved them back into the same hall at Shotts days before the slashing – a move described as an “oversight”.

Brady, 29, and Smith, 25, admitted at the High Court in Glasgow to assaulting Kergan to his severe injury and permanent disfigurement.

Both were already notorious knife thugs having each previously been found guilty of murder.

Brady was jailed for life in 2008 and ordered to serve a minimum 16 years after stabbing to death dad-of-one Brian McWilliams in the city's Govanhill.

Smith was sentenced to at least 19 years in 2010 after knifing George Mathieson through the heart in the killing in Cambuslang, near Glasgow.

The duo were have now been sentenced to another six years and three months to start after their life terms.

The slashing occurred on May 14 last year outside in the yard in high-security Shotts.

Kergan, 27, was also a lifer there having been locked up for 13 years for the brutal murder of Stephen Daly in Glasgow's Sighthill in 2005.

He had only recently been returned to Shotts following claims he had earlier assaulted Brady.