The US has closed its embassy in Kyiv after receiving “specific information about a potential significant air attack”.

The threat comes a day after Ukraine used US-supplied long-range missiles to strike a target inside Russia, taking advantage of newly granted permission from Joe Biden.

“Out of an abundance of caution, the Embassy will be closed, and Embassy employees are being instructed to shelter in place,” a statement from the US state department said.

“The US Embassy recommends US citizens be prepared to immediately shelter in the event an air alert is announced,” the alert added.

Early on Wednesday, Kyiv authorities said it had engaged air defences to repel an attack on the capital.