Police are investigating potential breaches of Covid-19 restrictions at a GAA match in Bellaghy on Sunday.
Complaints were made about a lack of social-distancing by some spectators at the Derry GAA senior club final.
Supt Int Mike Baird said police would be reviewing all available evidence “to determine any potential breach” of coronavirus regulations.
Derry GAA defended its handling of the final, and said it had made efforts to adhere to Covid-19 guidelines.
The county body said it had taken measures, including changing grounds, to ensure Covid-19 guidelines were followed.
It comes as the GAA announced that it has paused all club fixtures with “immediate effect”.
The organisation said the decision “has been taken in the interest of public safety following a number of incidents that have been brought to our attention in recent days”.
“In particular, post-match celebrations and a lack of social distancing at certain events have proved disappointing and problematic,” it added.
‘Disappointed and angry’
Health Minister Robin Swann said he was “disappointed and angry” at the scenes of spectators appearing to breach Covid-19 regulations at the game.
He told the assembly he welcomed that the GAA had now suspended all its games, but that he was concerned about the impact the event could have.
“I was angry to see it because if there’s one person in that group or community who has Covid-19 there is all chance it has spread among that group,” he said.
“I note the GAA have suspended all games and they’ve expressed disappointment – they’re claiming circumstances were beyond their control but I would have liked to see more stringent adherence to the guidance that was already in place.”
The minister also said that if there were further breaches, he would “encourage the police to investigate”.
The game between Slaughtneil and Magherafelt was moved from Londonderry’s Celtic Park to Bellaghy, in the Mid-Ulster Council area, after stricter Covid-19 restrictions were introduced in the Derry and Strabane Council area.
Derry GAA said it moved the game as it did not want spectators entering the city given the high rate of Covid-19 cases.
“It was an all-ticket event with restricted numbers and advice on GAA and health protocols were, including social distancing, widely communicated in the lead-up to and during the game,” the organisation said.
It added that it had taken the decision to “play an intermediate final and junior semi-final fixtures at the weekend behind closed doors as there were teams from the Derry City and Strabane Council playing in each of the games”.
Gary Middleton, a Foyle MLA, called on the GAA to “step up and show leadership” and noted his own constituency had rising case numbers. He called on the police to investigate.
DUP MLA Keith Buchanan, who represents the Mid-Ulster area, told BBC News NI’s Inside Politics programme that several members of the community in Bellaghy had sent him images of the crowd at the game.
He said he was not raising it as a political issue but one of personal responsibility and added that others would pay the price for the behaviour of the crowd, which he described as “out of control”.
Sinn Féin’s Linda Dillon told the programme that she had not seen the images but that if regulations have been broken then it should be looked at.
However, she paid tribute to the role local GAA clubs had played during the pandemic. She said she was sure the GAA would look at the scenes from the weekend and take a responsible attitude.
SDLP MLA Patsy McGlone also said he had not seen the images but that if there had been any braches then the Public Health Agency (PHA) should liaise with the GAA and investigate.
In a statement, Mid Ulster Council said it “would emphasise the need for everyone to behave responsibly”.
A spokeswoman for the council said that “enforcement responsibility lies with the PSNI”, and had previously called for people to follow guidance after Covid-19 guidelines appeared to be breached at a match involving Dungannon Clarkes.
Police have said they are investigating a GAA match in County Tyrone on Sunday 20 September to see whether Covid-19 regulations were breached.
Following the match, crowds came onto the pitch, leading to concerns about social distancing.
The council added it called on everyone to adhere to “the regulations and guidelines which are there to protect us all, especially as cases are rising”.
What are the rules about fans in a stadium?
Sporting events are omitted from rules that limit outdoor gatherings to 15 people, and some spectators are allowed – but within strict restrictions.
Under guidelines issues by the Department for Communities, spectators are required to be two metres apart..
A crowd management plan should be in place too, with a one-way system to avoid congestion as spectators enter and leave a stadium.
Where possible, ticketing and booking should be used, to allow for social distancing within seated venues.
A specific maximum number of spectators allowed is not given by the department.
Inside Politics Mid Ulster Q&A will be available to watch on the BBC News NI website from Monday evening and is broadcast on BBC Radio Ulster at 06:00 on Tuesday,