Image caption Earlier this week, Mike Nesbitt said leaving the Northern Ireland Executive was one of the options his party was considering

Ulster Unionist leader Mike Nesbitt will later make what is being called "a significant announcement".

It is understood the party's MLAs are meeting at Stormont.

Earlier this week, Mr Nesbitt said leaving the Northern Ireland Executive was one of the options his party was considering.

It follows claims the Provisional IRA was involved in the murder of Kevin McGuigan earlier this month.

Mr McGuigan Sr, a 53-year-old ex-IRA man, was killed in what police believe was part of a "fall-out" in republican circles after the murder of former IRA commander Gerard 'Jock' Davison in May.

Police said an infrastructure exists at a senior level of the Provisional IRA, but that there was no evidence that Mr McGuigan's murder was sanctioned by that hierarchy.