Vice-president of the EU Eva Kaili was arrested in Brussels on Friday evening by police investigating alleged lobbying by World Cup hosts Qatar at the European Parliament, Trend reports citing Daily Mail.
Greek socialist MEP Eva Kaili, 44, is being questioned after the arrests of four other people as officers searched 16 properties earlier on Friday.
This is said to include Ms Kaili's partner Luca Visentini, 53, who is the current General Secretary of the International Trade Union Confederation, ITUC.
It is understood that all four of those originally arrested are Italian citizens or of Italian origin.
Ms Kaili is a member of the Panhellenic Socialist Movement and was voted in as a vice-president in January 2022. She has been an MEP since 2014.
She recently called Qatar a 'frontrunner in labour rights' after meeting with the nation's labour minister, Politico reports.
The paper added Qatar is accused of targeting officials 'with a significant political and/or strategic position' at the Parliament, before sending them 'substantial amounts of money'.
This is despite international concerns about after it was revealed thousands of migrant workers could have died building the tournament's stadiums.
Belgium's federal prosecutor announced the earlier arrests after 600,000 euros in cash was discovered when police raided 16 addresses raids in the capital Brussels.
The prosecutors did not specify the identities of the suspects or name the country involved, saying only that it was a 'Gulf' state.
The searches were carried out as part of a wider investigation into 'criminal organization, corruption and money laundering,' and primarily targeted parliamentary assistants, the Belgian federal prosecutor's office said in a statement.
But a source close to the case confirmed press reports that it was focused on suspected attempts by Qatar to corrupt an Italian Socialist who was a member of the European parliament from 2004 to 2019.
This story is being updated.