KYIV, Sep 11 (Reuters) - Ukrainian forces kept pushing north in the Kharkiv region and advancing to its south and east, Ukraine's army chief said on Sunday (Sep 11), a day after their rapid surge forward drove Russia to abandon its main bastion in the area.

Ukrainian officials accused retreating Russian forces of launching retaliatory attacks on civilian infrastructure, including a thermal power station in Kharkiv, that the authorities in Kyiv said caused widespread blackouts.

"No military facilities, the goal is to deprive people of light & heat," Ukrainian President Volodymyr Zelenskyy wrote on Twitter of the attacks.

Moscow denies its forces deliberately target civilians.

Zelenskyy has described Ukraine's offensive as a potential breakthrough in the six-month-old war, and said the winter could see further territorial gains if Kyiv received more powerful weapons.

In the worst defeat for Moscow's forces since they were repelled from the outskirts of the capital Kyiv in March, thousands of Russian soldiers left behind ammunition and equipment as they fled the city of Izium, which they had used as a logistics hub.

Ukraine's chief commander, General Valeriy Zaluzhnyi, said the armed forces had regained control of more than 3,000 square km since the start of this month.

Moscow's almost total silence on the defeat - or any explanation for what had taken place in northeastern Ukraine - provoked significant anger among some pro-war commentators and Russian nationalists on social media. Some called on Sunday for President Vladimir Putin to make immediate changes to ensure ultimate victory in the war.