(BSS/AFP) - The European Union must ramp up measures against the Kremlin, including reviewing the issuance of tourist visas to Russians, to counter Moscow`s "hybrid attacks", foreign policy chief Kaja Kallas said Tuesday.

"Despite international efforts to end the war, (Russian President Vladimir) Putin chooses to intensify his war of aggression against Ukraine and hostilities against Europe, and one thing is very clear: Putin will not stop unless he is stopped," Kallas told the European Parliament.

"So, as Russia is willing to take greater risks, Europe must impose a greater cost."

Europe is grappling with what Kallas called a "steady increase in hybrid attacks" by Russia designed to weaken support for Ukraine.

Fears rose over the summer when an explosive-laden drone was discovered at a German airport in an incident Berlin blamed on Moscow.

Beyond ramping up support for Kyiv and sanctioning the Kremlin, Kallas said the EU should look to increase controls on Russians coming into the bloc.

"We can tighten control further over the movement of Russian diplomats within Schengen. We can ban issuing visas for Russian ex-combatants, and we should review the issuance of tourist visas to Russian citizens," she said.

"We must reduce the pool of people conducting attacks on European soil."

Kallas also urged EU states to better share intelligence and step up the use of artificial intelligence to tackle Russian disinformation.

While the EU eyes more measures, officials admit that the West is struggling to halt actions from Moscow that float in a grey zone beneath open conflict.

"We have all the response options we need when it comes to hybrid. It will not always be visible and public, what we do," NATO chief Mark Rutte said Monday.

"The most important one, of course, is making sure that Ukraine has what it needs to stay in the fight."