Police are investigating reports of large crowds on Belfast’s Shankill Road after Rangers won the Scottish Premiership.
People were pictured filling the area, despite a ban on public gatherings under coronavirus restrictions, to celebrate the Glasgow side’s first title in a decade.
The Police Service of Northern Ireland (PSNI) has indicated that “appropriate enforcement action” will be taken.
Superintendent Nigel Henry said officers received reports of a street party and flares and fireworks being set off on the Shankill Road, as well as fireworks in the Ballysillan Road area.
He described the scenes as “disappointing”.
“The numbers involved in the scenes last night were clearly a breach of the Health Protection (Coronavirus) Regulations, which is so disappointing when we know so many other people are adhering to the regulations and playing their part to keep people safe,” he said.
“An investigation is under way, and appropriate enforcement action will be taken in relation to breaches of the regulations.”
Northern Ireland has been living under a strict raft of rules aimed at stemming the spread of the virus since a spike of cases in December.
DUP MP Gregory Campbell urged fans not to break Covid rules on Sunday.
He said it would be a bad day for Rangers supporters if the title celebrations ended with people in intensive care beds.
“No-one is more delighted than myself to see this success for the Gers. It’s been a long road. But so has the battle against Covid,” he said.
“I understand the desire for celebrations but that doesn’t justify breaking the public health rules.
“There will be plenty of time to celebrate in due course when the vaccine has been rolled out.”
DUP leader Arlene Foster praised the club’s success.
She added: “It is very important that everybody abides by the public health regulations.
“We saw people in Belfast, people who were rightly jubilant about Rangers’ success in the Scottish Premier League.
“We have to abide by the public health regulations.
“They are there for a reason, to protect our communities.”