KYIV, Aug 31 (Reuters) - Ukraine told critics of the pace of its three-month-old counteroffensive to "shut up" on Thursday (Aug 31), the sharpest signal yet of Kyiv's frustration at leaks from Western officials who say its forces are advancing too slowly.

Since launching a much vaunted counteroffensive using many billions of dollars of Western military equipment, Ukraine has recaptured more than a dozen villages but has yet to penetrate Russia's main defences.

Stories in the New York Times, Washington Post and other news organisations last week quoted US and other Western officials as suggesting the offensive was falling short of expectations. Some faulted Ukraine's strategy, including accusing it of concentrating its forces in the wrong places.

Moscow says the Ukrainian campaign has already failed. Ukrainian commanders say they are moving slowly on purpose, degrading Russia's defences and logistics to reduce losses when they finally attack at full strength.

"Criticising the slow pace of (the) counteroffensive equals ... spitting into the face of (the) Ukrainian soldier who sacrifices his life every day, moving forward and liberating one kilometre of Ukrainian soil after another," Ukraine's Foreign Minister Dmytro Kuleba told reporters on Thursday.

"I would recommend all critics to shut up, come to Ukraine and try to liberate one square centimetre by themselves," he said at a meeting of EU foreign ministers in Spain.

NATO Secretary-General Jens Stoltenberg told CNN that Ukrainian commanders deserved the benefit of the doubt.

"Ukrainians have exceeded expectations again and again," he said. "We need to trust them. We advise, we help, we support. But ... it is the Ukrainians that have to make those decisions."