Russia has tightened controls on imports of cut flowers from the Netherlands, a move that comes amid a strain in ties over the downing of a Malaysia Airlines plane in Ukraine.

National veterinary agency Rosselkhoznadzor said Tuesday checks have repeatedly found Dutch cut flowers infested with pests. Starting Monday, imports of Dutch flowers will be allowed only after passing lab tests.

Russia has been accused of using sanitary issues as a pretext for politically driven bans.

Moscow has strongly opposed a Dutch-supported call for an international criminal tribunal on the July 2014 downing of Malaysia Airlines Flight 17 over Ukraine controlled by Russia-backed rebels. About two thirds of 298 victims were Dutch.

Last month, Moscow vetoed a draft U.N. resolution to set up the tribunal.