Independent Fingal County Councillor Anne Devitt said councillors had been in the chamber last night when the incident occurred but that she had been told the protesters jammed themselves between the panes and refused to move when requested to by gardaí.

A video of the incident appears to show a garda trying to move the revolving door while a woman’s voice can be heard shouting “you’ll break the door”. The glass is then heard shattering. A separate video shows a woman referred to as “Gina” with a blood injury to her head.

According to Right2Water-Swords Facebook page, Gina was one of four protesters, three women and one man, who “dodged past Garda lines” and “in the melee that followed a plate glass door was smashed by the garda”.

Ms Devitt said the increasingly hostile protests outside the council offices, including incidents of members and staff being barricaded into the car park, had led to a considerable increase in security over the past few months. The council has spent more than €30,000 on security since January 2013. Ms Devitt said last night councillors got “the usual level of abuse” and she did not consider it a “peaceful protest”. She described it as “anarchy and thuggery” and said taxpayers would end up paying for the repairs. She said it would be clear from CCTV footage at the council offices who was to blame.

In a statement, gardaí said the glass pane shattered as they were removing protesters “and a female protester received what is described as a minor cut to her head”.

The incident is under investigation by gardaí.

Separately two men were arrested during a protest by anti-water charge campaigners in Mallow, Co Cork. The two were part of the Mallow Says No group, which is preventing Irish Water contractors from accessing Woodview Drive in the town.

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