TANAISTE Joan Burton was smacked in the side of the head with a water balloon as a violent element hijacked water charge protests in west Dublin.
The incident happened as Ms Burton was attending a graduation ceremony at Cosan College, in Jobstown on Saturday.
A group of up to 1,000 protesters had gathered outside the college.
Video footage has emerged of Ms Burton walking from the building to a nearby church, where the next part of the ceremony was due to take place.
As she made her way up the street she was surrounded by mob holding placards and chanting "shame on you" and "we won't pay".
The footage showed that a red water balloon was thrown, from outside the camera shot, hitting the minister on the side of the head and bursting.
It is not clear from the footage who had thrown the balloon.
The assault clearly startles the minister, who continues to walk up the street, flanked by gardai.
Later, as Ms Burton was attempting to leave the college she became trapped in her car as the protesters surrounded her.
It is understood that she will not be making a formal compliant to gardai about the incident.
"She won't be making any comment other than this underlines that this was not the peaceful protest that [Anti Austerity Alliance TD] Paul Murphy said that it was," a spokesperson for Ms Burton told the Herald.
The Labour leader was audibly emotional as she yesterday recounted how around 100 protesters surrounded her car and banged on the roof and windows.
She said she hoped such standards would not become the norm, she said on RTE's Marian Finucane Show.
"They were rocking the car and banging on the windows and doors and roof.
"And Paul Murphy TD was standing at the back with a loudhailer leading the chanting," she said.
"If that's his idea of a peaceful protest I would not like to see that as a norm being set for Ireland by him as the way people in Ireland protest," she added.
However, Mr Murphy has claimed that the protest had been peaceful.
"Joan Burton is telling lies and there's video evidence that she is telling lies," he said on RTE radio.
"She's attempting to demonise what were peaceful protests. The protest and all the protesters were peaceful all the time."
"As there was no-one in charge I was the only TD there so they came to me. They put forward the idea that they should lead with a public order unit," he said.
"Then the Public Order Unit came in and she was allowed to leave at a slow pace.
"We didn't lose control of the demonstration. We took decisions together collectively after the protest ended and the gardai came in quite heavy handed with pepper spray afterwards," he added.
Two men, one aged 17 and the other 18, were arrested at the protest. A garda tyre was also slashed.
It emerged over the weekend that a new plan had been drawn up for the implementation of the charges. Under it, a one-adult household will face a charge of €76 a year for water.
Homes with more than one adult resident will pay €178, regardless of the number living in the home.
Irish Water has said that children's PPS numbers will not be required, just the householders.
In addition every home that registers will get a €100 payment - not just those on social welfare.