Ukraine and Russia: What you need to know right now

* At least seven people were killed and 70 injured in an attack by Ukrainian armed forces on Monday in the Russian-held town of Nova Kakhovka in the southern Kherson region, the Russian-installed administration there said.

Ukraine said it had carried out a long-range rocket strike against Russian forces and military equipment in southern Ukraine, killing 52 people in a territory it says it is planning to retake in a counter-offensive using hundreds of thousands of troops. FIGHTING * The death toll under a collapsed apartment block in the Donetsk region town of Chasiv Yar has climbed to 43, with rescue work still not over four days after the building was hit by Russian rocket fire, emergency services said. * At least 12 people were injured in shelling of the southern city of Mykolaiv overnight, the regional governor said. In the northeast, the mayor of Kharkiv, Ukraine's second city, told Ukrainian TV that it was under constant Russian shelling. * At least seven people were killed and 70 injured in an attack by Ukrainian armed forces on Monday in the Russian-held town of Nova Kakhovka in the southern Kherson region, the Russian-installed administration there said. Ukrainian officials said their forces had destroyed an ammunition depot in Nova Kakhovka. * Russian and Russian-backed separatist forces are encircling the town of Sieversk in Donetsk region, Russian state news agency TASS cited Rodion Miroshnik, ambassador to Moscow of the self-proclaimed Luhansk People's Republic, as saying. * Ukraine's general staff said Russia had unleashed a wave of bombardments as they seek to seize Donetsk, the other province in the eastern industrial Donbas region, after taking Luhansk to the north. It said the widespread shelling amounted to preparations for an intensification of hostilities. * Reuters could not independently verify battlefield accounts.

ECONOMY/DIPLOMACY * The European Union has so far frozen 13.8 billion euros ($13.83 billion) worth of assets held by Russian oligarchs, other individuals and entities sanctioned for Moscow's war against Ukraine, the bloc's top justice official said. * The global price of oil could surge by 40% to around $140 per barrel if a proposed price cap on Russian oil is not adopted, a senior U.S. Treasury official said. * Military delegations from Ukraine, Russia and Turkey will meet U.N. officials in Istanbul on Wednesday to discuss a possible deal to resume safe exports of Ukraine grain from the major Black Sea port of Odesa as a global food crisis worsens. * Ukraine's deputy infrastructure minister said grain shipments via the Danube River had increased with the reopening of the Bystre canal, which provides access to small inland river ports. It expects monthly grain exports to rise by 500,000 tonnes as a result. HUMAN IMPACT * The U.N. human rights office said more than 5,000 civilians had been killed in Ukraine since Russia invaded on Feb. 24, adding that the real toll was probably much higher.

(Compiled by Michael Perry and Mark Heinrich)