April 8 (UPI) -- Northern Ireland officials are expected to meet Thursday after the sixth straight night of violence between unionists and nationalists, during which rioters torched a bus and attacked police in Belfast.
The unrest started last week with unionist complaints about lack of police action against Sinn Fein party members accused of breaking coronavirus restrictions during a funeral for a former leader of the Irish Republican Army, or IRA.
Some of the violence stems from a lack of progress on issues related to Britain's exit last year from the European Union and the political and economic effect it has had on Northern Ireland, as it is geographically an EU entry point.
Unionists support Northern Ireland remaining as part of the United Kingdom, whereas nationalists favor the country uniting with Ireland.
Tensions reached new heights Wednesday night when a bus was set ablaze in the Northern Ireland capital, with both sides lobbing objects and gasoline bombs. Police struggled to keep both groups separated at a "peace line" in Belfast.
British Prime Minister Boris Johnson condemned the violence and called for dialogue over "criminality."
Mary Lou McDonald, president of Sinn Fein, called for unity among leaders to end the violence.
"Ongoing orchestrated violence must end," McDonald tweeted Thursday.
"Those stoking up tensions at interfaces must be faced down. Those inflicting violence held to account. Above all citizens and communities must be protected. Politics leaders must speak with one voice."
Northern Ireland First Minister Arlene Foster, who also leads the Democratic Unionist Party, blamed Sinn Fein for breaking the law and said any violence from both sides only fueled chaos.
"I have spoken with the chief constable as he briefs political parties," Foster tweeted Thursday. "Thoughts are particularly with those officers injured by the unjustified and unjustifiable violence of recent days.
"Those responsible must be subject to the full rigor of the law. All must be equal under the law."
Police Service of Northern Ireland Chief Constable Simon Byrne said more than 50 officers have been injured over the past six nights of violence.
"I am open to dialogue with anyone who is willing to work with me to resolve the issues facing our community," Byrne tweeted.
"My message to those engaged in violence tonight is go home before someone is seriously injured, violence is not the answer."