The United Nations says one million refugees have now fled Ukraine to neighbouring countries.

The exodus has taken place in just seven days. The Russian invasion began last Thursday.

As the BBC's Lewis Goodall points out: "The refugee crisis of 2015 involved 1.3 million. That's nearly been surpassed by the numbers from Ukraine in a week."

In a statement on Twitter, UN High Commissioner for Refugees Filippo Grandi pleaded for "guns to fall silent, so that life-saving humanitarian assistance can be provided" to the millions who remain in the country.

The agency has predicted the conflict will leave some 12 million people internally displaced and in need of relief.