Police in Belgium have arrested Greek socialist MEP Eva Kaili, one of 14 European Parliament vice-presidents, in connection with an investigation into criminal organization, corruption, and money laundering that involves an unidentified Gulf state.

Four others were also detained, including a former MEP, authorities said on Friday.

The Belgian federal prosecutor's office accused the unidentified Gulf country of trying "to influence the economic and political decisions of the European Parliament.''

Gulf lobbying at EU Parliament

Authorities believe the Gulf country tried to sway the European Parliament by "paying large sums of money or offering large gifts to third parties with a significant political and/or strategic position within the European Parliament."

Prosecutors did not name the country involved but Belgian publications Le Soir and Knack citing "several well-informed sources" reported Qatari officials were involved in trying to corrupt a former Italian MEP from the Socialists and Democrats group.

Investigators raided 16 addresses in Brussels as part of the investigation.

They recovered around €600,000 ($633,500) in cash and seized computer equipment and mobile phones.

A spokesperson for the European Parliament would not comment while an investigation was underway, but said the assembly was cooperating fully with police.

Kaili expelled from party

The Panhellenic Socialist Movement (PASOK) announced on Friday that it had taken the step to expel Kaili from the party.

"Following the latest developments and the Belgian authorities' investigation into corruption of European officials, MEP Eva Kaili is expelled from PASOK by decision of President Nikos Androulakis," the political party said in a statement.

Meanwhile, German Green MEP Daniel Freund tweeted a quote from Kaili from November this year in which she said told European Parliament: "I alone said that Qatar is a frontrunner in labor rights."

Freund went on to call the situation "appalling."

zc,kb,lo/aw (AP, AFP, Reuters, dpa)