The European Commission is being urged to investigate whether Hungary’s elections are being undermined by Russian manipulation, intimidation of journalists and voter coercion by the ruling party.

Three days before decisive parliamentary elections that threaten the 16-year grip on power of the prime minister, Viktor Orbán, a group of MEPs have written to the European Commission president, Ursula von der Leyen, and the commissioner responsible for the rule of law, Michael McGrath, calling for action.

The cross-party group want an urgent assessment “before and immediately after” polling day on whether the conditions for free and fair competition are being undermined by disinformation, foreign manipulation, state-resource misuse, intimidation of journalists and unlawful interference with opposition actors.

The appeal came as the European Commission demanded an urgent explanation from Budapest over a leaked recording that appeared to show a further instance of the Hungarian foreign minister covertly helping his Russian counterpart.

In their letter, MEPs cited a report by the independent media outlet VSquare that the Kremlin has dispatched a team to manipulate Hungary’s elections. The operation was reported to be overseen by Sergei Kiriyenko, the first deputy chief of staff to the Russian president, Vladimir Putin. Kiriyenko was alleged to have orchestrated a similar campaign in Moldova, where a massive vote-buying operation and troll farms were reported to have targeted the pro-EU president, Maia Sandu.

The journalist who wrote the report, Szabolcs Panyi, was subsequently accused by the Hungarian authorities of spying for Ukraine, and had been “targeted in a state-led intimidation of unprecedented severity”, the MEPs wrote.

The group also raised concerns over “credible allegations” of unauthorised attempts to access the opposition party’s IT systems, including by state security forces. They flagged well-documented reports of vote-buying and intimidation by the ruling Fidesz party, warning of a serious risk of voter coercion. “The union cannot credibly defend democracy externally while failing to react when the integrity of elections inside the union itself is placed under such serious strain,” they said.

The letter was sent as the commission demanded an urgent explanation from Hungary after another leaked phone call between the foreign minister, Péter Szijjártó, and his Russian counterpart, Sergei Lavrov, reignited concerns over Budapest’s relationship with the Kremlin.

In leaked recordings obtained by a consortium of investigative reporters, Szijjártó appeared to offer to send Lavrov a document about Ukraine’s EU accession.

“I will send it to you. It’s not a problem,” Szijjártó reportedly said, after Lavrov said that Moscow was trying to get a document about the role of minority languages in Ukraine’s EU accession talks.

Responding to the report, the French foreign minister, Jean-Noël Barrot, said it was “a betrayal of the solidarity” required between EU countries. Poland’s prime minister, Donald Tusk, said the recording was “really beyond shocking”.

On Thursday the commission’s chief spokesperson, Paula Pinho, said the recording raised “the alarming possibility of a member state coordinating with Russia, thus actively working against the security and the interests of the EU”.

She told reporters it was for “the member state’s government in question to explain itself as a matter of urgency” and that the president [von der Leyen] would raise the issue at leaders’ level.

Speaking before that statement, Tineke Strik, the Dutch Green MEP who leads the European parliament’s work on democratic standards in Hungary, said the commission had been “too hesitant” in dealing with Budapest. The commission, she said, was “very afraid” of being accused of interfering in Hungary’s elections.

She said Orbán was “using the EU anyhow in his attacks”, a reference to the government’s billboard campaign targeting European leaders, including von der Leyen and relentless anti-EU rhetoric from Orbán and his ministers.

The commission, Strik said, could be more outspoken to protect the interests of Hungarian citizens. “So far, they don’t do it. I understand their reasons, but they reason too much on the basis of a normal democratic process. And that’s the point that I make to them: we are not in a normal situation.”