A news conference by European Central Bank president Mario Draghi was briefly interrupted when a young woman charged at Draghi calling for an "end to the ECB dictatorship".
The woman who was wearing a T-shirt with the same slogan and appeared to be aged in her twenties, was quickly escorted out of the premises by security officers before the news conference resumed.
A startled Draghi held up his hands as protection, but was otherwise relatively unruffled. The news conference started again shortly afterwards.
Protester disrupts ECB president Mario Draghi's press conference https://t.co/Wb4ibqjW5I— RTÉ Business (@RTEbusiness) April 15, 2015
It was not clear where the woman was from or what her specific protest was.
Some Europeans are angry at austerity imposed on their countries by the European Union, backed up in some cases by ECB rules.
The ECB has frequently been the target of protests, but this was the first time a demonstrator has actually infiltrated the building and disrupted a news conference in such a manner.
Security in and around the ECB's headquarters is traditionally extremely tight.
Last month, dozens of people were injured when violent clashes between anti-capitalist protesters left a trail of destruction at the official inauguration of the ECB's new headquarters in the east of Germany's financial capital, Frankfurt.
The ECB had earlier left euro zone interest rates unchanged today, holding them at record lows as it rolls out a money-printing scheme to lift the economy.
The decision to leave the cost of borrowing at record lows was widely expected after the ECB cut rates to rock-bottom levels last September.
The bank's president, Mario Draghi, said at the time that rates had hit "the lower bound".
The ECB left its main refinancing rate, which determines the cost of credit in the economy, at 0.05% at its meeting today.
It also kept the rate on bank overnight deposits at -0.2%, which means banks pay to leave funds at the central bank, and held its marginal lending facility - or emergency overnight borrowing rate for banks - at 0.3%.
When his press conference resumed, Mr Draghi pledged to roll out its money-printing programme “firmly” and granted continued backing for Greece, saying there was no need yet to limit emergency funding for its banks.
Describing speculation that the fledgling €60bn a month scheme would be scaled back as "surprising", Mario Draghi underlined his determination to see through quantitative easing until September 2016, or until inflation was back up to target.
"Our focus will be on the full implementation of our monetary policy measures," Mario Draghi told a news conference after the ECB left interest rates at record lows.
Mr Draghi also said the deposit rate would not fall any lower. This sets a floor on which bonds it can buy as the ECB has said it will not buy bonds with a yield lower than -0.2% -matching the rate on overnight deposits made by banks.
Mr Draghi said help for cash-strapped Greece was an issue firmly in the hands of the Greek government, which has yet to produce an acceptable programme of economic reforms to unlock euro zone funds.
But he also said there was no immediate prospect of cutting off Greek banks' access to funding.
ECB policymakers sanctioned further Emergency Lending Assistance for Greece's banks of up to €74bn, a banking source said yesterday, a reminder of the dire financial straits that the country is in.
"We approved ELA and we'll continue to do so, extend the liquidity to the Greek banks while they are solvent and they have adequate collateral," Mr Draghi said, adding that there was no end date for such emergency assistance.
Time is running out for Athens to improve a package of reforms required for the release of loans that it requires to stay afloat.