Calls to reform lobbying rules for European Union institutions are growing as Brussels reels from a corruption scandal involving the European Parliament.
Greek MEP Eva Kaili, a vice president of the parliament, is among four charged amid the investigation into suspected influence peddling involving a Gulf country.
Belgian media have linked the probe to World Cup hosts Qatar; Doha has denied the accusations.
Kaili was arrested after Belgian police staged 16 raids across Brussels on Friday during which they recovered around €600,000 and seized computer equipment and mobile telephones.
The house of a second MEP, from Belgium, was also searched over the weekend but their identity has not been confirmed.
"It is a serious scandal, possibly the biggest ever. I think it is isolated in terms of its size, but I think there might have been smaller cases that have gone undetected in the past," Emilia Korkea-aho, a professor of European law and legislative studies at the University of Eastern Finland, told Euronews.
"If there is any silver lining to this, I think it is that the EU must seriously consider revamping its lobbying and ethics system," she added.
Lobbying is currently defined by the EU as "all activities (...) carried out with the objective of directly or indirectly influencing the formulation or implementation of policy and the decision-making processes of the EU institutions, irrespective of where they are undertaken and of the channel or medium of communication used".
The bloc has rules governing lobbying of its institutions, with at its core the so-called transparency register, a public database holding up-to-date information about those actively engaged in activities aimed at influencing EU policies.
The database now counts
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