Funerals for four of the 35 victims of a Russian missile attack on a Ukrainian military training center close to the Polish border have taken place.

Sunday's assault on the large Yaroviv military facility killed 35 people and wounded 134, according to local Ukrainian officials.

On Tuesday four soldiers who died in the attack were buried at Lviv's main cathedral, attended by family, friends, and fellow servicepeople.

Mourners wept as six young soldiers carried the coffins aloft, each preceded by a portrait of the fallen.

Regional governor Maksym Kozytskyy said Russian planes fired around 30 rockets at the Yavoriv facility.

The attack used air-launched cruise missiles fired from Russian airspace by long-range bombers, according to a senior U.S. defense official.

The official, who spoke on condition of anonymity, said the strike on the Yavoriv International Centre for Peacekeeping and Security, would not affect the West's military resupply effort for Ukraine.

Russia's defense ministry said the air strike destroyed a large amount of weapons supplied by foreign nations that were being stored at the sprawling training facility, and that it had killed "up to 180 foreign mercenaries."

The attack brought the conflict to the doorstep of the Western defense alliance.

Russia had warned on Saturday that convoys of Western arms shipments to Ukraine could be considered legitimate targets.

Ukrainian president Volodymyr Zelenskyy says at least 1,300 Ukrainian military personnel have been killed so far, although the figure could be much higher.