International Monetary Fund Managing Director Kristalina Georgieva said today that Ukraine likely needs $5 billion a month in financial assistance to keep its economy operating.

The immediate priority was finding ways to fill that gap in the next three months, the IMF chief said.

Georgieva told a news conference that despite uncertainty over Ukraine's future, the IMF will start work on a future IMF loan programme, but it was "unfair" to expect Ukraine to implement a far-reaching package of reforms at the moment.

The IMF chief also said today that it was a "difficult moment" for the Group of 20 economies with tensions over Russia's invasion of Ukraine.

But she insisted that G20 cooperation must continue to deal with pressing problems.

"We also recognise how interdependent we are - and just make the list of questions no country can solve on its own. And it is so obvious that cooperation must and will continue," the IMF chief added.