Football fans from the Republic ripped up seats and threw them onto the pitch as sectarian violence gripped Windsor Park last night.
Riot police moved into the away section housing Shamrock Rovers supporters at the Setanta Sports Cup quarter final against Linfield.
Bottles and other missiles were thrown by both sets of fans, and a number of flares were also flung onto the playing surface during the disorder which broke out midway through the first half.
Some Rovers fans broke through a barricade in the top deck of the North Stand and made their way towards Linfield fans. Police quickly contained the situation. Witnesses said sectarian chanting and goading could be heard from both sets of fans throughout the game.
After the match, a cordon of police vehicles blocked off Tates Avenue to keep fans apart.
They came under attack from youths throwing stones and bottles, although police said calm was restored quickly.
A loyalist flag protest was also said to be taking place in the area at the time.
It was not known last night if any arrests had been made.
"All I will say is that it was a sad night for football and if anything football was the loser," said Linfield manager David Jeffrey.
The trouble follows the arrests of two fans after disorder at the first leg between the two teams in Dublin last week.
Sectarian chanting reverberated around the Tallaght Stadium during the game and a Union flag was erected on a post inside the grounds.
Witnesses said a pocket of the Belfast club's fans clashed with gardai and security as they waited to go home.
There have been numerous clashes between fans of teams taking part in the all-Ireland Setanta Sports Cup since its inception in 2005.
SDLP MLA Conall McDevitt called on both clubs to take action against unruly fans.
"I'm disgusted that some Shamrock Rovers fans came to Belfast tonight to engage in sectarian chanting and violence.
"It has no place in sport," he said.
"The behaviour of a number of Linfield fans in Dublin was also deplorable. The) two clubs need to clamp down on those who are damaging the game."
Milo Corcoran, who is chairman of the Setanta Cup organising committee, added: "It's disgraceful to have that kind of carry-on."
The Setanta Sports Cup is a club football competition featuring teams from the football associations on both sides of the Irish border. It was inaugurated in 2005 for teams from the IFA Premiership in Northern Ireland and the League of Ireland in the Republic. The cup is sponsored by Setanta Sports, the Irish subscription sports television network.
The competition has seen numerous instances of crowd violence at its games since its inception.