Gardaí investigating a serious gang disturbance in central Dublin last weekend have appealed to people who witnessed it, and may have recorded video footage on their phones, to come forward.

Investigating gardaí have now ruled out any connection between the incident and possible violence that had been warned about at the Longitude festival in south Dublin last weekend.

While the three-day festival passed off without incident, there were concerns before it that two factions of young men in their late teens and early 20s may clash at the concert.

Gardaí came into information that suggested threats had been issued by one of the groups against the other in the build-up to Longitude.

While that information was analysed by the Garda officers planning the security operation around Longitude, sources said the information was not of sufficient concern to significantly alter the policing plan.

However, the US embassy learned of the information and issued a warning to its citizens. That warning urged US citizens in Dublin to be aware of their surroundings as there had been reports of a “potential for violence” at Longitude in Marlay Park, Rathfarnham.

In the early hours of Sunday morning a large group of men tried to rush the door at the Lost Lane venue, formerly Lillies Bordello, on Adam Court off Grafton Street.

A security guard was injured and when the alarm was raised and gardaí arrived the group of men, which numbered about 20, dispersed.

A follow-up search in the general Grafton Street area yielded an assortment of weapons including knives, hatchets and petrol bombs.

In the immediate aftermath of the incident gardaí were trying to establish if the incident outside Lost Lane was linked to the “potential for violence” that the gardaí had analysed and the US embassy had learned of in advance of Longitude.

However, investigations have determined the incident off Grafton Street was not related to the two groups it was feared may clash at Longitude.

Such was the scale of the incident outside Lost Lane that the Garda’s Serious Crime Unit in Pearse Street Garda station has been tasked with investigating it. Those detectives are now appealing for information or footage from anyone who was in the Adam Court area from 12:30am to 1:30am on Sunday.

A Garda statement said a number of people were in a smoking area close to where the disturbance occurred and some of them may have been recording events on their mobile phones. Anyone with information is asked to contact Pearse Street Garda station or any other station.