European Union foreign ministers will adopt sanctions Tuesday against Russia over its recognition of Ukrainian separatist regions and further deployment of troops on its neighbour's territory, the bloc's foreign policy chief Josep Borrell said.

"Of course our response will be in the form of sanctions, whose extent the ministers will decide... I'm sure there will be a unanimous decision" required for the measures, Borrell told reporters in Paris.

He added that the text of the possible measures was being prepared during the morning while the ministers attend a forum with Indo-Pacific nations in the French capital.

The decision itself would come "this afternoon" at an emergency meeting that he has called on the sidelines of the forum in Paris, Borrell said.

Borrell would not be drawn on the details of the sanctions, which are expected to fall on the same day as punitive measures by the US and Britain.

Washington has already banned US persons from any financial dealings with the breakaway territories in eastern Ukraine whose independence was recognised by Russian President Vladimir Putin late Monday.

Shortly after the announcement, Putin ordered troops into the two regions as part of a "peacekeeping" operation.

"Russian troops have entered Donbas, we consider Donbas part of Ukraine," Borrell said Tuesday.

But the EU joined the US in holding off describing the deployment as an invasion that would trigger the harshest sanctions threatened by the West in recent months.

"I wouldn't say that's a fully-fledged invasion, but Russian troops are on Ukrainian soil," Borrell added.