McCartney's sisters challenge Sinn Fein

They challenged Sinn Fein to ensure that condemnations of violence by the Republican leadership meant there would be less Republican violence on the ground.

The Sinn Fein leader, Gerry Adams, accused the party’s opponents of trying to smear them by linking the Republican movement with criminality.

McCartney was stabbed and beaten after a row in a Belfast city bar on January 30.

The IRA has expelled three members following an internal investigation into claims by the family that Provisionals killed the East Belfast man, covered evidence up and intimidated witnesses from going to the police.

Last Thursday Adams suspended seven members of the party amid claims that they were involved. The suspensions could become expulsions if the members are found guilty in any legal process arising from the case.

But Republicans have been reluctant to go to the police with information about the killing because of Sinn Fein’s refusal to endorse Northern Ireland’s new police service.

Catherine McCartney said they hoped that their presence at the conference would help efforts to get justice. She noted Sinn Fein chief negotiator Martin McGuinness’s insistence at the party conference on Friday night that Republicans were outraged by the murder.

"It does appear Republicans are beginning to address this," she said. "However, at the end of the day it is what happens on the ground that really matters over our brother’s murder.

"We need a situation where what the Republican leadership are saying reflects what is being done on the ground."

Adams, meanwhile, called on Republicans to test again whether the Rev Ian Paisley really is willing to share power with them in Northern Ireland.

In an address to his party conference, he accused opponents of trying to demonise his party with allegations of criminality.

He also rejected claims that Sinn Fein regarded the IRA Army Council as the legitimate government of Ireland or that it had a warped view of what criminality was.