Dissident republican terrorists planned to use a rocket launcher to kill Northern Ireland's Deputy First Minister, it has been revealed.
Martin McGuinness said he was warned of the CIRA (Continuity) IRA plot by the Police Service of Northern Ireland (PSNI).
In a statement, Mr McGuinness said: "I have been made aware the PSNI has discovered a plan to launch a rocket attack against me.
"The PSNI has said that a group calling itself 'CIRA' considered an attack against me using a rocket launcher."
A decision by Mr McGuinness to meet the Queen in 2012 caused outrage among hardline dissident republicans opposed to the peace process in Northern Ireland.
He has since met the Queen on three occasions including as a guest at a Windsor Castle banquet last year.
The Sinn Fein MLA added: "I will not be silenced or deterred. These people are only interested in plunging us back into the past.
"If those behind this threat think they have the ability to destroy the peace agreements which have been endorsed by the overwhelming majority of the people of Ireland then they are clearly detached from reality.
"They need to wise up, listen to the people of Ireland and abandon these futile actions.
"This threat will not stop me or anyone in Sinn Fein from our work in representing everyone in our society and continuing to pursue our political objectives."
The CIRA split from the Provisional IRA when it declared a ceasefire in 1994.
While the IRA moved towards decommissioning of arms, the CIRA's aim remained to kill members of the security forces in pursuit of its goal of a united Ireland.
The terror group's most notorious action was the murder of police officer Stephen Carroll in March 2009. The 48-year-old was shot dead as he attended a call for help at a housing estate in Craigavon, Co Armagh.
The officer, originally from Co Kildare in the Irish Republic, was hit by a sniper and became the first police fatality since 1998, the year of the Good Friday Agreement which largely ended three decades of conflict.
Earlier this year 12 suspected CIRA members were arrested during a police raid at a house which had been bugged by MI5 for months.
A number of suspects have appeared in court charged with a range of terror offences linked to the operation at Ardcarn Park, Newry in Co Down.