|Paula McCartney, center, sits next to her sisters Gemma, left, and Chatherine during Group of the Party of European Socialists session|
The police warning of threatened arson attacks on the relatives of Robert McCartney has come just days after the European Parliament endorsed funding for a civil suit against his suspected IRA killers.
The McCartney sisters say police told them the threats came from "criminal elements," but the authorities did not elaborate.
The sisters have led a high-profile international campaign for justice in the murder, including a meeting with President Bush at the White House in March.
In reaction to the latest threats, one of the sisters, Paula McCartney, says the family will not be intimidated.
"It's absolutely scandalous, ridiculous, that the victims are being terrorized," she said.
Robert McCartney was a 33-year-old Catholic man and father of two children. He was stabbed and beaten to death outside a Belfast bar on January 30 following an argument with some IRA members.
Witnesses have refused to cooperate with authorities, despite appeals from the IRA's political wing, the Sinn Fein party. The IRA expelled three members for alleged involvement in the crime. It also has offered to shoot the killers. The McCartney sisters have rejected the offer. Sinn Fein also has expelled several members said to have information about the murder.