Canada joined Australia, Britain and the United States in a diplomatic boycott of the Winter Olympics in Beijing on Wednesday, with China calling the boycotts "political posturing" and a smear campaign.

Japan will not send a government delegation to February's Winter Olympics in Beijing, it said on Friday, a move likely to deepen tension with China.

The Chernobyl nuclear power plant has been captured by Russian forces, an adviser to the Ukrainian presidential office, Mykhailo Podolyak, said on Thursday.

Ukraine said on Friday it had recorded increased radiation levels from the defunct Chernobyl nuclear power plant, a day after the site was captured by Russian forces, due to military activity causing radioactive dust to rise into the air.

The European Union has asked its satellite centre in Madrid to provide intelligence to Ukraine about Russian troop movements and EU countries are determined to further increase their bilateral military support to Kiyv, the EU's head diplomat said.

The United States has expelled 12 Russian diplomats at the United Nations over national security concerns, U.S. and Russian diplomats said on Monday.

The European Union has approved new sanctions against Belarus for its supporting role in Russia's invasion of Ukraine, effectively banning about 70% of all imports from that country, the EU said on Wednesday.