Kiev, Sep 2 (IANS/EFE): Ukrainian forces have engaged in fierce fighting against pro-Russian militias in the eastern Ukrainian regions of Donetsk and Lugansk, the Ukrainian military command reported Tuesday.

The government forces killed 50 pro-Russian militants and destroyed a Grad missile launcher and two armoured vehicles, the command said without mentioning casualties in the Ukrainian ranks.

"The pro-Russian militias are massing in the towns of Komsomolskoye, Vasilyevka and Rozdilna," the command said in a statement.

"Terrorists who wear the uniform of the Russian army" attacked Ukrainian units carrying out medical evacuation of the wounded, the command charged.

Ukrainian forces are battling between 10,000 and 15,000 armed opponents, including militia and regular Russian troops, according to the spokesman for the National Security and Defence Council of Ukraine, Andrei Lysenko.

Lysenko said that he could not specify the exact number of the Russian soldiers in Ukrainian territory, because the numbers change daily.

The pro-Russian militias recently launched a major counteroffensive that forced the Ukrainian troops to retreat from several strategic points, including the Lugansk international airport.