Ukrainian President Petro Poroshenko has told MPs that the military should prepare to defend against a Russian invasion of great magnitude, as eastern Ukraine has been suffering from recent surges of violence.

Russia has denied that its forces have been deployed on Ukrainian ground, but President Poroshenko refutes that point and estimates 9,000 Russian soldiers already in sovereign ground.

Clashes involving main battle tanks (MBTs) took place in two areas near Donetsk this week. The outbreak of violence has been felt even more in the government-held towns of Krasnohorivka and Maryinka in the east.

The separatists, on their part, deny any violation of the truce.