Belgium on Friday announced it is probing Russian "interference" in the European Parliament following allegations that lawmakers took money to spread Kremlin propaganda ahead of the June EU elections.
The Czech Republic last month said its intelligence service had discovered a network that used EU lawmakers to spread Russian propaganda through the Prague-based Voice of Europe news site.
Belgium says it has determined that some of the lawmakers had been paid to promote Moscow's propaganda.
"The cash payments did not take place in Belgium, but the interference does. As Belgium is the seat of the EU institutions, we have a responsibility to uphold every citizen's right to a free and safe vote," Belgian Prime Minister Alexander De Croo said.
A summit of EU leaders next week will discuss the allegations, raised two months ahead of the June 6-9 bloc-wide elections to vote in a new European Parliament.
De Croo said Moscow's "clear" objectives were to "help elect more pro-Russian candidates to the legislature and reinforce the pro-Russian narrative in that institution".
Belgium's federal prosecutor's office confirmed to AFP that the probe into foreign individuals or organisations suspected of giving "donations, loans or advantages" to gain influence started on Thursday.
The crime carries penalties ranging from six months to five years in prison and a fine of between 1,000 and 20,000 euros ($1,050-$21,250).
"If there would be a type of bribery -- and our services indicate that payments have taken place -- while you need two sides for that to happen, you have people who organise it, but you also have people to receive it," De Croo said.
The European Commission has issued repeated warnings about Moscow spreading disinformation and misinformation ahead of the EU polls, and seeking to weaken European public support for Ukraine as it fights off Russia's invasion.
Tactics go beyond publishing outright false information, EU officials have said. Mixing in nuggets of facts into false stories can confuse or mislead readers so that they distrust all news sources -- including reputable ones.
Voice of Europe, whose internet site is still accessible, is known for publishing stories repeating Russian messaging and giving airtime to guests who do so.
One of its top executives is a Ukrainian oligarch, Viktor Medvedchuk, who is close to Russian President Vladimir Putin and who has been sanctioned by the Czech government along with the outlet itself.
On Friday, Voice of Europe put a statement on its site saying it was being "unfairly and ruthlessly stigmatised" along with "European farmers, politically rising anti-globalist parties, supporters of these parties, former US president Donald Trump (and) Hungarian Prime Minister Viktor Orban".
It blamed "unpopular globalist 'elites', their discredited lackeys in the lying mainstream press, and those financed by (US financier and philanthropist George) Soros," who is a bete noire of Orban's.
Trump and Orban have sent chills down spines in Brussels for their stances more in favour of Moscow than supporting Ukraine.
The Greens grouping in the European Parliament and a Czech daily said the lawmakers under suspicion of voicing Russian propaganda on Voice of Europe came from Belgium, France, Germany, Hungary, the Netherlands and Poland.
EU lawmakers face strict rules regarding independence and ethics and can face penalties -- financial and otherwise -- if they violate them.
The political news website Politico said it identified 16 EU lawmakers who had appeared on Voice of Europe, all of them far-right politicians.
The Czech newspaper Denik N and Germany's Der Spiegel magazine named two top German candidates from the far-right Alternative for Germany (AfD) party, Petr Bystron and Maximilian Krah, as politicians suspected of receiving Russian funds to spread the Kremlin talking points.
Denik N reported that Czech secret services had an audio recording implicating Bystron, and that some politicians were paid to fund their EU election campaigns.
Bystron and Krah have denied receiving any payments.
The European Parliament's main political groups have called for the legislature to also probe the alleged propaganda-peddling.
The revelation comes a year after the "Qatargate" bribery scandal, in which a number of EU lawmakers were accused of being paid to promote the interests of Qatar and Morocco.
Both states deny the accusations.
