Ukraine pierces Russian border, triggering fierce clashes

MOSCOW, Aug 7 (Reuters) - Russia said on Wednesday it was fighting intense battles against Ukrainian forces that had penetrated its southern border near a major natural gas transmission hub in one of the largest incursions into Russian territory since the war began.

Russia has advanced this year after the failure of Ukraine's 2023 counteroffensive to achieve any major gains, and has taken 420 sq km (162 sq miles) of territory from Ukrainian forces since June 14, Russian officials say.

Ukraine struck back on Tuesday, and battles continued through the night into Wednesday as Ukrainian forces pushed to the northwest of the border town of Sudzha, 530 km (330 miles) southwest of Moscow, Russia's defence ministry said.

"The Kyiv regime has launched another major provocation," President Vladimir Putin told members of the Russian government, referring to the attack in Russia's Kursk region.

The chief of Russia's general staff, Valery Gerasimov, told Putin that Russian forces had halted a thrust by up to 1,000 Ukrainian soldiers - more than three times the figure that Russia's defence ministry had stated on Tuesday - and would push them back to the border.

"The enemy's advance deep into territory in the Kursk direction was stopped by the actions of the units covering the state border together with border guards and reinforcement units, with air strikes, missile and artillery fire," Gerasimov said in televised comments.

The Ukrainian military appears to have adopted a strategy of strict silence on the situation at the border and its General Staff has not acknowledged any operation is under way.

It said in its daily battlefield update that Russia had stepped up the use of warplanes against Ukraine’s Sumy region across the border from Kursk region, dropping at least 30 bombs. Ukrainian regional military officials announced mandatory evacuations of civilians from more than 20 border settlements.

Sudzha is the last operational trans-shipping point for Russian natural gas to Europe via Ukraine: the Urengoy–Pomary–Uzhhorod pipeline carried about 14.65 billion cubic metres of gas in 2023, or about half of Russia's natural gas exports to Europe.

Ukraine's gas transmission operator said Russian natural gas was transiting to European consumers normally. Just 60 km away to the northeast is Russia's Kursk nuclear power station.

The battles around Sudzha come at a crucial juncture in the conflict, the biggest land war in Europe since World War Two. Ukraine is losing territory and Kyiv is deeply concerned that U.S. support could drop off if Donald Trump wins the November election in the United States.

Trump has said he would end the war, so both Russia and Ukraine are keen to gain the strongest possible bargaining position on the battlefield. Ukraine wants to pin down Russian forces and show the West it can still mount major battles.

Russian military bloggers reported intense battles with some suggesting that Ukraine had opened a new front. Russia has sent reserves to help shore up its defences.

Gerasimov said Russia had inflicted heavy losses on the Ukrainian attackers in terms of men and equipment, giving figures that Reuters was unable to independently verify.

Putin said Ukrainian forces were firing "indiscriminately" at a range of civilian targets in the region.

Both Kyiv and Moscow say they do not target civilians in the war, triggered by Russia's full-scale invasion nearly two and a half years ago.

Russian Telegram channels carried unverified footage of shelled houses. Alexei Smirnov, the acting governor of the Kursk region, said there were casualties but gave no exact toll, and called on citizens to donate blood.

Forces describing themselves as voluntary paramilitaries fighting on Ukraine's side penetrated parts of Kursk and the adjacent Belgorod region earlier this year, triggering a major push by Russian troops to carve out a buffer zone in Ukraine's northeast.