Vladimir Saldo, the head of the Russian-installed administration in occupied parts of Ukraine's Kherson province, released video of himself on the Chonhar road bridge, where craters had been blasted through the asphalt.

"Another meaningless act perpetrated by the Kyiv regime on orders from London. It solves nothing as far as the special military operation is concerned," he said, vowing to repair the bridge and restore traffic.

He threatened to retaliate by targeting a bridge linking neighbouring Moldova to NATO-member Romania: "A very serious response is coming very soon."

The Chonhar bridge hit overnight is one of just a handful of access roads to Crimea, which is linked to the Ukrainian mainland by a narrow isthmus.

Alternative routes require hours-long detours over roads in poor condition. Russia's RIA new agency quoted Russian-installed transport officials in Crimea as saying repairing it could take weeks.

The bridge is beyond range of the battlefield rockets Ukraine has used for a year, but within reach of newly deployed weapons such as British and French air-launched cruise missiles, allowing Kyiv to hit logistics routes Russia had deemed safe just weeks ago.

'PSYCHOLOGICAL IMPACT'

The strike was "a blow to the military logistics of the occupiers," said Yuriy Sobolevsky, a Ukrainian official on the governing body for the Kherson region.

"The psychological impact on the occupiers and the occupying power is even more important. There is no place on the territory of Kherson region where they can feel safe," he said.

Russian investigators said four missiles had been fired by Ukrainian forces at the bridge, the RIA news agency reported. It quoted a spokesman for military investigators as saying that markings found on the remains of one of the missiles suggested it had been made in France.

Ukraine is attacking Russian supply lines to disrupt Moscow's defence of occupied territory in the south, where Kyiv is in the early stages of its most ambitious counteroffensive of the war.

Kyiv says it has recaptured eight villages so far, but it has yet to commit the bulk of its forces to the fight and its advancing troops have yet to reach the main Russian defensive lines.

In its latest update on the fighting, Ukraine's military reported "partial success" in the southeast and east.

Troops were reinforcing positions they reached after attacking towards the villages of Rivnopil and Staromayorske, said General Staff spokesman Andriy Kovaliov, referring to settlements in a Russian-held area where Ukrainian forces pushing south have so far captured four villages.

He also described fierce fighting in the east, where Ukraine says it has been holding off Russian attacks.

Russia says it has fended off the Ukrainian counterattack and inflicted heavy casualties, which Ukraine denies.

Ukrainian President Volodymyr Zelenskiy has acknowledged that progress has been slow so far, but says his troops are advancing cautiously into heavily mined and well-defended areas to minimise losses.

Zelenskiy on Thursday accused Russia of planning a terrorist attack on the Zaporizhzhia nuclear power plant, Europe's largest, which is in Russian-held territory near the front line. Moscow denied any such plan.