Ukraine's border was a powerful tool whether they were used or not.

This was by the way not the "planned spring phase of military training" as the Kremlin asserts but an unprecedented deployment of combat-ready forces designed specifically to threaten the Kiev government.

Air force drills

The Kremlin statement also reiterated Moscow's demand that the Kiev administration stop its military activities against the separatists and withdraws its troops.

Kiev said it was checking the reports of a Russian border withdrawal but also urged Moscow to call off an air force exercise planned for south-west Russia between Wednesday and Sunday, saying the drills would fuel tension ahead of Sunday's Ukrainian presidential election.

Two eastern Ukrainian regions - Donetsk and Luhansk - declared independence last week after a referendum.

image copyright AFP image caption Ukrainian troopson the road near Sloviansk in the east

image copyright Reuters image caption Preparations are continuing for Sunday's presidential election

The self-proclaimed Luhansk People's Republic on Monday said it would halt all preparations for the presidential election on its soil, deeming the poll "illegal".

Ukraine's PM Arseniy Yatsenyuk admitted polling in some eastern districts would be difficult, but added: "It affects very few areas... The election will take place and we will have a legitimate president."

Mr Putin has welcomed initial talks between Kiev and some of the separatists and has termed the presidential election a "step in the right direction".

However, violence continues in some parts of the east.

One Ukrainian soldier was killed and one injured on Monday in an attack by separatists on a checkpoint near Sloviansk, in the Donetsk region,