A former pro-British paramilitary leader in Northern Ireland , who turned police informer, was Monday sentenced to at least six-and-a-half years in prison for 202 terror offences including five murders.

Ulster Volunteer Force (UVF) unit leader Gary Haggarty, 46, struck a deal that saw him receive a reduced prison term in return for admitting the murders and giving evidence against fellow paramilitaries, one of whom is to be prosecuted over a murder as a result.

Judge Adrian Colton at Belfast Crown Court called Haggarty's case one of "exceptional gravity".

"He has been involved in a terrorist campaign over a 16-year period. That campaign has resulted in deaths for which he was directly responsible," he said.

"The organisation he supported and assisted has resulted in untold damage to individual lives and society as a whole."

His sentence was reduced from 35 years to six-and-a-half years as a result of cooperating with the police for 11 years and for pleading guilty.

As well as the five murders, Haggarty admitted five attempted murders during the period 1991 to 2007.

During his time as an informant, Haggarty provided information on 55 loyalist murders and 20 attempted murders.

The UVF officially ended its activities in the wake of the 1998 peace agreement, but authorities say they remained active in drug running, extortion and violence.

Based in Protestant, working-class communities, the group fought republican paramilitary groups such as the Irish Republican Army (IRA) during the three decades of violence in the province known as The Troubles, which claimed more than 3,500 lives.