The European Union has imposed asset freezes on top Russian officials, including Alexander Bortnikov, chief of the country’s federal security service and Mikhail Fradkov, head of its foreign intelligence agency.

They are among 15 people and 18 companies targeted for supporting Russia’s annexation of Crimea.

Further sanctions are expected be agreed as early as Monday.

After months of hesitation, the EU toughened its stance towards Moscow after last week’s downing of a Malaysian airliner in an area of eastern Ukraine held by separatists said to be backed by Russia.

Most of the passengers killed on the plane were Dutch citizens.

Dutch Prime Minister Mark Rutte said: “There are strong indications that the Russians are continuing to arm the rebels.”

“One of the questions was how Russia can avoid the sanctions. That is very simple,” said Rutte, adding, “they have to distance themselves from the separatists and to stop arming them.”

The prime minister announced on Thursday that the Netherlands is sending 40 unarmed military police officers to eastern Ukraine as part of a boosted efforts to find the last victims of the downed flight.