Arrests implicit alleged corruption astatine the European Parliament are "very, precise worrisome", the EU's overseas argumentation main Josep Borrell has said.
And Irish Foreign Affairs curate Simon Coveney said the charges against 4 people were "very damaging".
Among the arrested was European Parliament Vice President Eva Kaili - believed to beryllium 1 of those charged.
Prosecutors fishy a Gulf authorities - reportedly Qatar - tried to power parliament by donating wealth oregon gifts.
Qatar has denied misconduct.
Belgian constabulary seized currency worthy astir €600,000 ($632,000; £515,000) successful 16 searches successful Brussels connected Friday. Computers and mobile phones were besides taken, to analyse their contents.
Four radical person been charged portion 2 person been released, prosecutors said connected Sunday.
"They are charged with information successful a transgression organisation, wealth laundering and corruption," the Belgian national prosecutor's bureau said successful a statement.
Ms Kaili - an MEP for 8 years - was suspended from her duties arsenic 1 of 14 vice-presidents by president of the European Parliament Roberta Metsola.
She has besides been suspended from the parliament's Socialists and Democrats Group, and expelled from the Greek centre-left Pasok party.
Prosecutors successful Greece person reportedly frozen each of Ms Kaili's assets.
Watchdogs and absorption MEPs said the bribery probe could correspond 1 of the biggest corruption scandals successful European Parliament history.
"Certainly the quality is very, precise worrisome," Mr Borrell told reporters connected Monday arsenic helium arrived astatine a gathering of EU overseas ministers.
"We are facing immoderate events, immoderate facts, that surely worries maine arsenic a erstwhile president of the European Parliament."
Mr Borrell said the probe did not people anyone from the EU's diplomatic service.
Also speaking earlier Monday's meeting, Mr Coveney said the allegations were "very damaging", adding that "we request to get to the bottommost of it".
Meanwhile Terry Reintke, who co-chairs the Green bloc successful parliament, has called for Ms Kaili's contiguous resignation.
"We shouldn't adjacent person to region her from her vice president position," the German MEP said. "This should beryllium done by her proactively."
Prosecutors said they suspected a Gulf authorities had been influencing economical and governmental decisions of the parliament for respective months, particularly by targeting aides.
Local media has named the authorities arsenic Qatar, though the Qatari authorities said immoderate claims of misconduct were "gravely misinformed".
Ms Kaili's responsibilities arsenic vice-president see the Middle East. She has been a defender of Qatar successful the past.
Ms Metsola flew from her autochthonal Malta to Brussels connected Saturday evening to witnesser the searching of an MEP's location - arsenic is required by the Belgian constitution.
Her spokesperson said the European Parliament "stands firmly against corruption" and is "fully cooperating" with investigators.
The European Parliament is the EU's lone directly-elected institution. Some 705 members of parliament, elected by voters successful the 27 nations which marque up the EU, conscionable to scrutinise projected authorities and ballot done European law.