Russia has sent additional forces to the border with Ukraine and could launch an invasion at any time, including during the Winter Olympics, said US Secretary of State Antony Blinken, Reuters reported.

According to him, Washington continues to reduce the persons of its embassy in Ukraine, and repeated the State Department's call for American citizens in Ukraine to immediately leave the country.

"Simply put, we continue to see very troubling signs of Russian escalation, including new forces arriving at the Ukrainian border," Blinken said at a press conference in the Australian city of Melbourne.

The US State Department urged Americans in Ukraine to leave the country immediately amid what it called increased threats of Russian military action, and Blinken said Washington would continue to close its embassy. "We will continue that process and we've also been very clear that any American citizens who remain in Ukraine should leave now," Blinken added.

Russia has repeatedly denied plans to invade Ukraine, which the West insists on.