India, July 30 -- Ukrainian forces hit two of Russia's biggest oil refineries overnight in its latest long-range strikes, officials said, as Kyiv deepened its economic, military and diplomatic pressure on Moscow.

Ukraine's almost daily long-range drone and missile strikes using domestically developed weapons have battered Russian oil facilities for months. The operation has brought a fuel crisis that is embarrassing the Kremlin more than four years after Russia's all-out invasion of its neighbour.

The overnight attacks started fires at a Lukoil refinery in Russia's Perm region, more than 1,500 kilometres (900 miles) from Ukraine, and a refinery in Ryazan, about 400 kilometres (180 miles) from the border, Ukraine's Security Service and G...