​​​​​​​HAMILTON, Canada

Canada temporarily closed its embassy in Kyiv following a US advisory about a "potential significant air attack" on Ukraine, according to a media report Wednesday.

The advisory, which urged citizens to shelter during air alerts, was followed by similar closures of the Spanish, Italian and Greek embassies in Ukraine, according to CTV News.

The warning came one day after Ukraine, for the first time, attacked the Russian territory with US-made ATACMS missiles.

CTV News said Ukraine's military intelligence agency dismissed the warning as Russian misinformation and "this message is a fake."

It advised citizens, however, to remain cautious and heed air raid sirens.