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BRUSSELS (Reuters) - NATO Secretary General Jens Stoltenberg called on Russia on Wednesday to use its “considerable influence” with rebels in eastern Ukraine to end what he described as “the most serious spike in violations” of a shaky truce there in a long time.

Speaking to reporters, Stoltenberg said the ceasefire in eastern Ukraine has been violated more than 5,600 times in recent days, leaving some 20,000 people without electricity amid freezing temperatures.

He called for the respect for the so-called Minsk peace agreement for eastern Ukraine and for fulfilling its key provision that envisages a withdrawal of heavy weaponry from the area.