BELFAST (Reuters) - A leading member of a major Northern Ireland paramilitary group that said it got rid of all its weapons six years ago was shot dead in Belfast on Sunday, sparking fears of a fresh feud that could raise tensions in the British-controlled province.

Local media named the deceased as John Boreland, who was injured in a previous murder attempt two years ago. Boreland was a member of the Ulster Defence Association (UDA) whose scrapping of weapons in front of independent monitors in 2010 completed the disarming of Northern Ireland's main militant groups.

A 1998 peace deal largely ended three decades of bloodshed between Catholic Irish nationalists, seeking union with Ireland, and predominantly Protestant unionists who want to remain part of the United Kingdom, but pockets of violence remain.

A murder linked to former Irish nationalist militants led to a political crisis last year between the former foes who jointly run the power sharing executive when it raised questions about whether the province's ceasefire was being properly adhered to.

A report complied by Northern Ireland's police force and the British domestic intelligence agency MI5 following that episode found that all the main paramilitary groups, including the UDA, remained in existence but were not planning attacks.

It said groups on both sides of the divide were instead engaged in violence and other criminal activities, including fuel-laundering, drug dealing and extortion, and that members of all groups had carried out murders since the 1998 agreement.

On the UDA, the report concluded that while parts of its leadership were committed to steering it toward peaceful, community based activism, they had limited control over members who remained heavily involved in violence and crime and "act almost completely autonomously".

Sunday's murder was condemned by politicians on all sides, some of whom have expressed concern over the implications for the peace process from Britain's vote to leave the European Union, particularly if it leads to any hardening of the border between Northern Ireland and the Irish Republic.

(Reporting by Ian Graham, editing by Padraic Halpin and Guy Faulconbridge)