The Garda’s Public Order Unit, or riot squad, has been put on alert to respond to major public order incidents at popular beaches and coastal villages in Dublin in an effort to prevent a repeat of the scenes witnessed in Howth yesterday.

Local gardaí and members of the Public Order Unit were forced to move in and disperse several hundred teenagers that had gathered at Howth pier, many of them consuming large amounts of alcohol.

The Dart serving the village was suspended for a period to prevent the crowd increasing.

A large amount of alcohol was confiscated and gardaí said significant numbers of those who made their way to the unofficial gathering were intoxicated and “behaving in a threatening and abusive” manner.

“If you were out for a relaxing walk down by the water, you wouldn’t have lingered too long once you saw this kind of crowd,” said one source.

Gardaí believe messages were sent out on the SnapChat app encouraging teenagers to go to Howth for the afternoon, in the same way that crowds of teenagers descended on Howth and the nearby beaches of Malahide and Portmarnock last summer, resulting in serious public order issues.

“It seems to be an end of school term thing and has also happened a few times later in the summer holidays in the past few years,” said a senior Garda .

“The idea is that kids from all over Dublin would arrive on one spot, they go drinking and basically try and take over a place because there is so many of them.”

Yesterday when local gardaí and those from the Public Order Unit responded as the teenagers began to gather, sections of the crowd dispersed and others left when their alcohol was confiscated.

Gardaí called to local pubs and off licences asking them to be vigilant in requesting proof of age identification and to make sure they were not selling alcohol to any young people who were already drunk.

Traders were also urged to refuse to sell alcohol to anyone, even those aged 18 years or older, who they believed were buying it to take to the gathering in Howth.

Following a request by gardaí, the northbound Dart service did not stop in Sutton from 4pm to 6pm yesterday as part of the crowd control measurements.

While the Garda was criticised for its failure to deal quickly with incidents of this nature last year, their response to yesterday’s events appeared fast and well organised.

Ray Olohan, bar manager in Wrights Findlater, located opposite the west pier, in Howth, said the crowds of teenagers had been “intimidating because of the numbers” but said there had been a “very, very strong police presence” who had moved the groups of teenagers on and eventually dispersed the group.

Tommy Gaffney, local publican and shopkeeper and member of the local Chamber of Commerce and director of Howth Tourism said gardaí “seemed to have the situation well under control”.

“We experienced this last year as well where social media takes hold and they announce that they’re heading to Howth for the day...and they come in big numbers,” he said, adding that, while this was a “new phenomenon” it was one that local gardaí were aware of and were monitoring.

Garda sources said reinforcements, including the Public Order Unit, would be on call to be drafted in to deal with any similar incidents on Dublin beaches in the months ahead, saying the experiences of last year had been analysed for the purposes of planning a better response.