Traffic cones and glass bottles were thrown by protesters taking part in a water charges demonstration outside Leinster House on Wednesday night when a large force of gardaí had to clear the way for Oireachtas members leaving the car park.

A female garda was knocked unconscious after being struck by an object and was brought to St James’ Hospital with non-life threatening injuries, a Garda spokesman said.

Two men were arrested during the demonstration, and former minister for justice Alan Shatter accused protestors of being "fascist" when his car was surrounded as he attempted to drive through the front gates of Leinster House in the early stages of the protest.

The two arrested men, one in his 30s and another in his 50s, were charged and released and will appear in court at a later date.

The Dáil’s Committee on Procedures and Privileges met to discuss the incidents. It has requested to hear from the Garda Commissioner, Noirín O’Sullivan, why members were blocked from entering and leaving Leinster House.

Labour Senator Mary Moran said she had to abandon her car on Kildare Street. “It was completely vicious,” she said. “What the demonstrators were directing at the gardaí was something else. My car was surrounded and the gardaí were trying to stave them off.

“People were spitting at the car, and the car was hit by flying objects. There were children there and they thought it was hilarious when someone threw a traffic cone at my car and it hit a garda. People were laughing and taking videos and all sorts.”

Kildare Street and Molesworth Street in front of Leinster House were closed to traffic for a time. Approximately 50 gardaí were on duty at 9.30pm when a number of TDs and Senators began to leave in their cars. Gardaí formed lines to create a corridor for the vehicles to exit through. The crowd chanted “shame” at TDs as they departed.

One woman shouted: “You all have homes and we can easily find them.”

Gardaí drew their batons at one stage of the evening and some protestors were struck.

Earlier, when Mr Shatter attempted to enter the Leinster House car park through the Kildare Street entrance, up to 20 demonstrators surrounded his car. He later said the protestors involved were “intolerant, anti-democratic and fascist”.

He told The Irish Times: "The crowd gathered around the car and starting shouting abuse. They were shaking the car. Some of them felt the need to kick the car. At the start of the incident, four gardaí simply stood there and observed."

Mr Shatter said he was forced to make a series of phone calls to secure a Garda response and action. He said he would be bringing the matter to the Garda Commissioner’s attention.

A Garda spokesman said it would be inappropriate to comment on Mr Shatter’s allegation as an investigation would be launched after a complaint was made.

Speaking afterwards, activist and academic Kieran Allen said: “This is not fascism – this is democracy. People have every right to protest in a strong and peaceful way.”

He said there was a backdoor to Leinster House through which TDs could exit.

A 60-year old woman named Catherine, who would only give her first name, said: “We all linked arms but the guards started pushing – not all the guards but some. Others came in from behind. I saw this one man getting absolutely horsed out of it, and I nearly lost a shoe myself.”