Dissident republicans were planning to launch a deadly rocket attack against Deputy First Minister Martin McGuinness, it has emerged.
The senior Sinn Fein man revealed last night that the PSNI uncovered the plan and informed him.
He described the group behind the threat as "a group calling itself CIRA", or the Continuity IRA.
Mr McGuinness stated determinedly that he will not be "silenced or deterred" by the threat.
He first revealed the threat on his Twitter page, before Sinn Fein issued a statement revealing more details about the murder plot.
"These people are only interested in plunging us back into the past," he said in the statement.
"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."
Mr McGuinness said those behind the threat needed 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," he said.
This is not the first threat from dissidents against Mr McGuinness, who is a former commander in the IRA in his native city of Derry.
Advised by Police tonight of a threat to my life by so called CIRA.I take all threats seriously but won't be deflected in my work for Peace.— Martin McGuinness (@M_McGuinness_SF) February 9, 2015
He has admitted being the organisation's second-in-command on Bloody Sunday in 1972 when civil rights protesters were shot dead by paratroopers.
In 2013 Mr McGuinness spoke of a "real and active" threat against his life from dissident republicans.
At that time, he said that he believed the threat was linked to his public condemnation of an attempted mortar attack in Derry and comments in support of the PSNI.
He said then: "It says much about the mentality of those controlling groups like the one behind the threat that in their warped logic, threatening Irish republicans and their families somehow advances the cause of Irish reunification.
"I am very sure of the ground I stand on.
"I am also very sure that it is the path shared by republicans across this island genuinely interested in building a new agreed Ireland, republicans who put Ireland before ego, criminality and self-gain." Dissidents view him as a traitor and one of their main hate figures for going into government with unionists and endorsing the police service.
Graffiti condemning him has also appeared in his home city.
He has repeatedly called on all the various dissident republican groups to disband.
In 2012 he made history by shaking hands with the Queen as she visited Belfast.
He went on to shake her hand again when he attended a State banquet at Windsor Castle in 2014.
The Deputy First Minister is not the only member of Sinn Fein to receive death threats.
Sinn Fein president Gerry Adams faced a numbers of death threats from dissidents from 2006 onwards. Last November he also received threats from loyalists. North Belfast MLA Gerry Kelly has also been threatened on several occasions.
Alliance Policing Board member Trevor Lunn condemned those behind the threat.
He said: "There is no justification for making a threat against the life of any individual.
"Every politician should be able to carry out the work that they were elected to do without having to worry about being attacked. Any threat against an elected representative is an attack on democracy. All parties must unequivocally condemn this threat and any other attempt to intimidate any elected representative."