She spoke after Nathalie Tocci, a 42-year old Italian academic and a special advisor to EU foreign policy chief Federica Mogherini, appeared on on Russian state broadcaster RT on Monday, prompting criticism.

RT played up Tocci's EU credentials with the headline: "If I were Iran, I would want to pull out of the JCPOA as well - Mogherini's adviser".

The Joint Comprehensive Plan of Action (JCPOA) is the name of an Iran nuclear arms control deal, part-negotiated by the EU.

But the headline twisted Tocci's remarks to make it sound like the EU was trying to provoke its ally, the US, in an ongoing dispute on Iran.

The RT interviewer, a celebrity correspondent called Sophie Shevardnadze, also played up internal EU divisions in the half-hour segment.

She asked question after question on whether far-right parties were gaining power, if Brexit would end in disaster, and if Hungary and Poland would block integration, forcing Tocci on the defensive.

And Mogherini's advisor said nothing on Russia's war in Ukraine or on the Kremlin's anti-EU propaganda campaign.

Tocci spoke on RT just three days after the European Commission, of which Mogherini is a vice-president, published a report accusing Russia of "sustained disinformation activity ... aiming to suppress turnout and influence voter preferences" in last month's European Parliament elections.

"There was a consistent trend of malicious actors using disinformation to promote extreme views," the commission said.

The EU foreign service also has dozens of entries for RT in its Russian propaganda database, posing questions on Tocci's wisdom in taking up Shevardnadze's invitation.

"We're shocked [that she did it], given the problem of propaganda and disinformation from the Kremlin side," an EU official told Polish Radio on Wednesday.

Tocci's interview was "a betrayal" and RT was "a Kremlin propaganda tube", Jakub Janda, a Czech expert on Russia at the European Values think tank in Prague, also said.

Special advisors are paid by EU institutions and "work on a short-term basis for a very limited number of days per year", according to commission literature.

Some EU commissioners have several of them, but Mogherini has only Tocci, whose brief was to assist her on "the implementation of the European Union global strategy ... supporting global governance and the United Nations".

Tocci is director of a Rome-based think tank called the International Affairs Institute and was once spoken of as a potential foreign minister by the Russia-friendly 5 Star Movement party in Italy.

She stayed quiet on her Twitter account on the RT controversy this week.

But for some, the RT story told a tale about Mogherini's own weak handling of Russia in her past five years in office, despite the EU foreign service's comment on Tocci's distant status.

"Nathalie Tocci's interview with Russian propaganda outlet RT constitutes a symptomatic summary of Mogherini's term - very little clue about Russia," Daniel Szeligowski, from the Polish Institute of International Affairs, a think-tank in Warsaw, said.