"The United States and other NATO countries are deliberately turning Ukraine into a powder keg," Deputy Foreign Minister Sergei Ryabkov was quoted as saying by Russian news agencies, adding that countries were increasing their arms supplies to Ukraine.

Clashes between Ukrainian forces and Moscow-backed separatists in eastern Ukraine have escalated in recent weeks, upending a ceasefire brokered last year.

Following an uptick in violence, Russia has built up troops along the border, raising fears of a major escalation in the long-running conflict in Ukraine's mainly Russian-speaking east.

"If there is any aggravation, we of course will do everything to ensure our security and the safety of our citizens, wherever they are," Ryabkov said.

"But Kiev and its allies in the West will be entirely responsible for the consequences of a hypothetical exacerbation," he added.

On Tuesday morning, a Ukrainian soldier was killed and two more injured near the village of Mayorske some 35 kilometres (21 miles) north of the separatist stronghold Donetsk when a drone dropped grenades on the positions of Kiev's troops, the military said.

The latest casualty brought the number of Ukrainian troops killed since the start of the year to 29, compared to 50 in all of 2020.

Ukrainian Foreign Minister Dmytro Kuleba was in Brussels on Tuesday, where he met with NATO chief Jens Stoltenberg.

Kuleba was also set to meet with US Secretary of State Antony Blinken in Brussels later Tuesday.

Ahead of the visit he said he wanted to discuss Western support for Ukraine.

"Already now we need to talk about practical support that Ukraine can get in case of a large-scale armed escalation," Kuleba said in televised remarks late Monday.

The Kremlin, which has not denied the troop movements along the border, has said it is not planning to go to war with Ukraine, but also added that it "will not remain indifferent" to the fate of Russian speakers in the east.