The attack on the Filanovsky rig - part of Russia's largest Caspian oil field - is the latest sign that Ukraine is trying to step up its campaign to disrupt Russian oil and gas output.
At least four drone strikes hit the platform, forcing extraction to stop at more than 20 oil and gas wells, the official said.
The Filanovsky field, discovered in 2005, was inaugurated by Russian President Vladimir Putin in 2016 and produces about 120,000 barrels per day.
Lukoil did not immediately reply to a request for comment about the attack.
It was unclear where the Ukrainian military launched the attack from but the Caspian Sea is more than 700km from Ukraine's nearest border.
Ukraine has conducted numerous drone strikes on Russian oil facilities this year in an effort to undermine Russia's ability to finance its war in Ukraine.
The strikes have particularly targeted oil refineries, many of which are situated in the European part of Russia.
Ukraine widened its campaign last month by targeting unregulated tankers transporting Russian oil through the Black Sea.
Three such vessels have been hit by Ukrainian sea drones in the last two weeks.
At least seven blasts have struck other tankers that called at Russian ports since December 2024 in locations including the Mediterranean.
Ukraine has neither confirmed nor denied any role in those attacks.
Russia, which launched a full-scale invasion of Ukraine in February 2022, has accused Ukraine of piracy and threatened to retaliate by cutting off Ukraine's maritime access in response to attacks on tankers.
The commander of Ukraine's drone forces said on Thursday that they had also hit two chemical plants in Russia's Novgorod and Smolensk regions.
Major Robert Brovdi said on the Telegram app that the chemical plants were producing components for explosives used by Russian troops fighting in Ukraine.
Russian Foreign Ministry spokeswoman Maria Zakharova said on Thursday that the United Kingdom needed to disclose what one of its soldier killed in Ukraine on Tuesday was really doing there, accusing the UK of helping Ukraine carry out "acts of terrorism".
The UK Ministry of Defence said on Tuesday that the soldier, Lance Corporal George Hooley, died in Ukraine while observing Ukrainian forces test a new defensive capability away from the frontline.
Zakharova said the government should not deceive its citizens by claiming that UK soldiers sent to Ukraine were mere advisers or instructors, accusing UK forces of helping Ukraine "carry out terrorist attacks and extremist tasks" on direct orders from authorities in London.
The UK government, one of Ukraine's staunchest supporters, has never confirmed how many service personnel are in Ukraine but the BBC has reported that a small contingent is supporting Ukrainian forces and is providing security to diplomatic staff.
