Russian forces were "bogged down" trying to capture the northeastern border town of Vovchansk but fighting on the eastern front has been intense, Ukrainian army chief Oleksandr Syrsky said Friday.

After initial success, "the enemy has got completely bogged down in street battles for Vovchansk and suffered very high losses in assault units," Syrsky said, but added that fighting near the eastern cities of Chasiv Yar, Pokrovsk and Kurakhove was "intense".