Russian full-scale invasion of Ukraine in 'next 24 hours', warns Australian PM Scott Morrison

A Russian invasion of Ukraine is “likely to occur within the next 24 hours”, Australia's Prime Minister Scott Morrison has warned.

"The invasion of Ukraine has effectively already begun. They’re acting like thugs and bullies. Australians always stand up to bullies and we will be standing up to Russia," he told reporters in Sydney, adding Australia is also preparing to add to sanctions against the Kremlin.

It comes as Ukraine urged all its citizens to leave Russia "immediately".