Eva Kaili, a Greek MEP, has denied involvement in a World Cup host country Qatar-related bribery scandal at the European Parliament.
After discovering €1.5 million (£1.3 million) in two homes and a suitcase, Belgian investigators charged four suspects, including her.
By a vote of 625 to 1, MEPs decided to remove Ms. Kaili from her position as one of its 14 vice presidents.
Roberta Metsola, the speaker of the parliament, has mentioned “difficult days for European democracy.”
“[Eva Kaili] declares her innocence and that she has nothing to do with bribery from Qatar,” her lawyer, Michalis Dimitrakopoulos, told Greek TV on Tuesday.
There was uncontested evidence, he added in a later statement, that “every move, contact and statement made by Eva Kaili regarding Qatar was made in execution and application of the official policy of the European Union”.
Prosecutors carried out a string of searches over several days and said cash worth about €600,000 had been found at the home of one suspect, €150,000 at the flat of an MEP and €750,000 in a suitcase in a Brussels hotel room.
Belgian police released a photo on Tuesday showing piles of notes in €200, €50, €20 and €10 denominations.
Sources said the €150,000 was found at Ms Kaili’s flat. Asked if that was true, her lawyer said: “I have no idea if any money was found or how much was found.”
The suspects arrested by Belgian police have been charged with “participation in a criminal organisation, money-laundering and corruption”, prosecutors said on Sunday. They will appear before a pre-trial court on Wednesday.
The allegations have cast a shadow over the role of lobby groups at the European Parliament. A recommendation to allow visa-free travel to the EU for Qataris was set to be voted on by MEPs this week, but has now been shelved.
Searches have taken place in Italy as well as in Brussels. Since Friday, the IT resources of 10 parliamentary employees have been “frozen” to prevent the disappearance of data necessary for the investigation.
Parliament, sitting in Strasbourg, voted overwhelmingly on Tuesday to strip Ms Kaili of her role as vice-president. The door to her office in the parliament building was sealed with a notice saying “access forbidden”.
She has also been suspended from the parliament’s Socialists and Democrats Group and expelled from the Greek centre-left Pasok party.
Greek authorities have frozen assets belonging to her, her husband and immediate family members.
The activities of a property company set up about two weeks ago by the MEP and her partner in Athens have also been frozen.
Six people were detained on Friday as part of the investigation into allegations that Qatar bribed EU officials to win influence. Two were later released.
The three others accused are all Italian citizens. Ms Kaili’s partner, Francesco Giorgi, who is a parliamentary assistant, is among those reportedly charged.
Former MEP Pier Antonio Panzeri, who now runs human rights group Fight Impunity, is also among the four, sources say. His wife and daughter were also reportedly arrested. Mr Giorgi had formerly worked for him as a parliamentary assistant.
The other suspect, according to Italian news agency Ansa, is Niccolò Figa-Talamanca. He runs lobby group No Peace Without Justice, which is housed in the same building in Rue Ducale in Brussels’ European quarter.
The head of the general secretary of the International Trade Union Confederation, Luca Visentini, was questioned and later released. He said later he had been able to answer all questions put to him.
BBC Brussels correspondent Jessica Parker says details released by Belgian authorities in the last few days left many people’s jaws on the floor in EU circles.
MEPs who spoke to our correspondent said they were shocked by both the scale and blatancy of the accusations.
Ms Metsola said ahead of the vote to strip Ms Kaili of her leading role at the Parliament that “European democracy is under attack and our free and democratic societies are under attack”. She and the Parliament would do everything they could to fight corruption, she added on Tuesday: “There will be no impunity, there will be no sweeping under the carpet.”
Watchdogs and MEPs said the bribery investigation could represent one of the biggest corruption scandals in the parliament’s history.
Prosecutors said they suspected a Gulf state had been influencing economic and political decisions of the parliament for several months, especially by targeting aides.
Although reports widely named the state as Qatar, the Qatari government said any claims of misconduct were “gravely misinformed”.
Ms Kaili’s responsibilities as vice-president included the Middle East.
The World Cup in Qatar is proof, actually, of how sports diplomacy can achieve a historical transformation of a country with reforms that inspired the Arab world.
Last month, while other colleagues drew attention Qatar’s human rights violations, she gave an effusive speech to the parliament praising Qatar for hosting the World Cup and for its role as a “frontrunner in labour rights”.
Addressing a debate in the Parliament on Tuesday, EU Home Affairs Commissioner Ylva Johansson said there was an initial presumption of innocence but this was now a serious criminal investigation: “To anyone accepting payoffs kickbacks, bribes, I say shame on you… for violating the trust of the people of Europe.”
Green MEP Daniel Freund, who heads a cross-party anti-corruption group, told the BBC that the parliament had “reasonably good lobby transparency rules” but that third countries like Qatar were excluded from them: “So I think these third countries should go on the lobby register.”
The European Parliament is the EU’s only directly elected institution. Some 705 members of parliament, elected by voters in the 27 nations which make up the EU, meet to scrutinise proposed legislation and vote through European law.
MEPs generally enjoy immunity from prosecution, but not in cases where “a member is found in the act of committing an offence”, the parliament says.