Britain's defense ministry says Russia has been increasingly using anti-aircraft missiles against land targets in Ukraine, raising concerns over the possibility of increased civilian casualties.

Russian missile attacks have been killing and injuring civilians in Ukraine.

The British ministry said in its intelligence update on Friday that Russia has increased its use of air defense missiles because of "critical shortages of dedicated ground-attack missiles."

The report says Russia has almost certainly deployed S-300 and S-400 air defense systems near Ukraine. The systems are designed to shoot down targets at long ranges.

It says "There is a high chance of these weapons missing their intended targets and causing civilian casualties" because "they are not optimized for this role, and their crews will have little training for such missions."

At a security forum organized by a US think tank on Thursday, the chief of Britain's secret intelligence service MI6, said the Russians are about to run out of steam in Ukraine.

Richard Moore said the Russian military would find it increasingly difficult to supply manpower and material over the next few weeks.

Moore said Russian troops will have to pause in some way, and that will give the Ukrainians opportunities to strike back.

The Russian military continued attacks in eastern Ukraine on Thursday.

Ukrainian emergency authorities and local media say Russian forces shelled a school and residential areas in Kramatorsk in the Donetsk region and the Kharkiv region, killing four civilians and injuring more than 20.