The National Dialogue Quartet in Tunisia has won the Nobel Peace Prize, it has been announced.

The Norwegian Nobel Committee cited the group for its "decisive contribution to the building of a pluralistic democracy in Tunisia in the wake of the Jasmine Revolution of 2011".

"It established an alternative, peaceful political process at a time when the country was on the brink of civil war," the committee said in its citation.

The quartet is made up of four key organisations in Tunisian society: the Tunisian General Labour Union; the Tunisian Confederation of Industry, Trade and Handicrafts; the Tunisian Human Rights League; and the Tunisian Order of Lawyers.

"The Nobel Peace Prize for 2015 is awarded to this Quartet, not to the four individual organisations as such," the committee said.

The prize is a huge victory for Tunisia and its young and still shaky democracy.

It suffered two terrorist attacks this year - including a beach massacre that left dozens of tourists dead - including three Irish people.

A total of 273 candidates were nominated for the 2015 prize, five fewer than in 2014.

Pope Francis was among the nominees for this year's award, as was German Chancellor Angela Merkel.

Last year, education campaigner Malala Yousafzai - who was shot in the head by the Taliban in Afghanistan - was named the joint winner.

While Irish scientist Dr William C Campbell was jointly awarded this year's Nobel Prize for Medicine.