Russian forces on Friday launched a ground assault on Ukraine's northeastern Kharkiv region, advancing near the border town of Vovchansk, a senior Ukrainian military source said.

The assault opens a new front in the conflict which began in 2022.

Kyiv said it had sent more forces to the area as reinforcements.

Ukraine chased Russian troops out of most of the Kharkiv region in 2022, but after weathering Kyiv's counteroffensive last year, Russia forces are back on the attack and are slowly advancing in the Donetsk area further south.

Fears grew in March over Moscow's intentions when Russian President Vladimir Putin called for the creation of a buffer zone inside Ukrainian territory that he said was needed to protect Russia.

Since then, Kharkiv, which is particularly vulnerable because of its proximity to Russia, has been hammered by air strikes that have caused major damage to its power infrastructure.

In Vovchansk, a Kharkiv region border town with a pre-war population of 17,000 that has dwindled to a few thousand, officials said the settlement and surrounding areas were under massive shelling and authorities were helping civilians evacuate. (Reuters)