Russian forces are stepping up attacks in eastern Ukraine and have reportedly made small gains to capture a Ukrainian stronghold in the Donetsk region, but with continued attrition on manpower and equipment.

Russian and Ukrainian forces appear to be locked in battles going back and forth in the region.

The British defense ministry said in its intelligence update on Saturday that "Russia has highly likely made small advances on the southern axis" of its assault on the town of Bakhmut during the past several days.

It said that the Russian campaign "has been disproportionately costly relative to these possible gains."

Ukrainian President Volodymyr Zelenskyy called the situation in Bakhmut "the hottest" and "most painful."

He said his government will do everything to help the troops in that area. He also said the government is strengthening its forces in Luhansk and Kharkiv regions also in the east.

Russia's Defence Ministry says that Defence Minister Sergei Shoigu visited neighboring Belarus and met President Alexander Lukashenko on Saturday.

Shoigu reportedly met his Belarusian counterpart Viktor Khrenin and signed a document to amend an agreement on regional security. Details of the document have not been disclosed.