Aug 7 (Reuters) - Kyiv kept up air attacks on Russia's

Kursk border region on Wednesday, with defence systems

destroying four drones overnight, the Russian defence ministry

said, a day after Moscow accused Ukraine of targeting the area

with an armoured assault.

The ministry had sent reserves on Tuesday to help repel

hundreds of Ukrainian fighters backed by tanks from Kursk, in a

ground incursion shaping as one the largest into Russian

territory during the war, now more than two years old.

The situation was "controllable", Alexei Smirnov, the acting

governor of the southwestern Russian region, said in posts on

the Telegram messaging app.

All emergency services were on "high alert", he said on

Wednesday, calling for people to donate blood to replenish

medical supplies.

The region was under a dozen air raid alerts over the past

24 hours, Smirnov's posts showed. By Wednesday morning, there

were no reports of fresh ground fighting.

Five people were killed, including two ambulance crew, with

at least 20 wounded, among them six children, in the fighting

that erupted on Tuesday, Russian officials said.

Ukraine made no official comment, though there was evidence

of some military action from its side of the border. Both Kyiv

and Moscow say their attacks do not target civilians.

Ukraine regularly fires artillery and missiles into Russian

territory, and has hit targets deep inside Russia with

long-range attack drones, but infantry raids are rare.

Forces describing themselves as voluntary paramilitaries

fighting on Ukraine's side inflicted minimal damage in a major

incursion into parts of Belgorod and Kursk region this year, but

the purpose of the raids remains unclear.

On Tuesday, Ukraine's general staff made no mention of any

Ukrainian offensive operation inside Russia.

Official Russian social media accounts said up to 300

Ukrainian fighters, backed by tanks, had attacked border units

in two localities in Kursk - Nikolayevo-Daryino and Oleshnya.

Reuters was unable to verify the battlefield accounts of

either side.

ATTACK ON AMBULANCE

Officials said the border town of Sudzha had also come under

assault and Smirnov said a Ukrainian attack drone had hit an

ambulance outside the town, killing the driver and a paramedic

and wounding a doctor.

A senior Orthodox clergyman said Ukrainian shelling had set

ablaze a cathedral and other buildings within a large monastery

outside Sudzha, but no one was hurt.

Kursk region is also the site of the Kursk Nuclear Power

Plant, but Smirnov said the facility was operating without

incident.

Russia's air defence systems destroyed also three drones

that Ukraine launched at Belgorod region and two each over the

Voronezh and Rostov regions, the defence ministry said.

In the Voronezh region - several hundred kilometres

south of Moscow - the drones damaged several residential

buildings and cars, the regions' governor said on Telegram.

Ukraine's main military effort is focused on pushing back

Russian military forces who control nearly a fifth of its

territory. Russian troops have made a series of gradual gains in

the past six months.