Threats made to Sinn Fein leaders
A series of threats have been made targeting senior Sinn Fein members ahead of the election.
Deputy First Minister Martin McGuinness's home was paint bombed while party president Gerry Adams was warned that a bomb had been left at his family home in west Belfast, but police found nothing untoward.
Officers have stepped up patrols targeting dissidents opposed to the peace process and the danger to the security forces is rated as severe.
Mr Adams said: "In recent weeks there has been a concerted series of threats and attacks on the homes of Sinn Fein members.
"There can be no place for these type of actions nor will they deter Sinn Fein from working to advance the peace process and advance our political objectives.
"Sinn Fein will not be intimidated."
It follows an upsurge in attacks and threats against Sinn Fein figures that the party blames on dissident republicans.
Mr McGuinness said: "It was also an attack on the wider democratic process coming just a day before the Westminster election, carried out by so-called dissident republican elements."
In Derry, cars belonging to two Sinn Fein councillors were attacked overnight, one set alight and the windows of another smashed.
Two men, aged 17 and 23, have been arrested on suspicion of criminal damage.
Police Service of Northern Ireland Assistant Chief Constable Stephen Martin told BBC Radio Foyle: "These attacks pose a risk to lives. They are reckless.
"Martin McGuinness had his house attacked with paint this week. When you add all that up, then there is a high probability that this is all linked to the election ."
Two leading members of Sinn Fein, MEP Martina Anderson and Stormont Assembly member Raymond McCartney, received bomb warnings at their homes in Londonderry.
Mickey Brady, who is running for MP in Newry and Armagh, and Assembly member Conor Murphy have also been threatened.
Mr McGuinness said the perpetrators showed contempt for the will of the people.
"I am calling on all the community to defend the progress and gains of the peace process and to reject those intent on dragging us back to the past."