A wave of relentless Sunday drone attacks out of Ukraine on Crimea has resulted in a regional cut off to civilian access to fuel, in another sign that UAV attacks on Russian territory are having serious effect.

Four people were killed in the series of drone strikes on energy and transport infrastructure in the Russian-controlled peninsula, including attacks near Kerch, a key eastern Crimean port city which is a major energy logistics hub.

"As a result of the enemy's drone attack on the Kerch Peninsula, unfortunately, there are casualties among the civilian population," Crimean Governor Sergey Aksyonov announced.

"According to the latest information, four people were killed, 28 were wounded," he added.

And he also confirmed the fuel crisis for the whole region, saying, "Today, June 21, starting from 09:00 am, fuel sales at Crimean petrol stations have been suspended" - though he added that fuel would only be sold to state enterprises.

He made clear in a Telegram post that starting Sunday morning local time gas stations across the peninsula would stop selling fuel to individuals and businesses. All cash, card and fuel coupons were immediately halted.

Ukraine's President Zelensky boasted of the attacks, stating on social media that "Facilities on both sides of the Crimean Bridge were hit: maritime logistics used to transport oil in the Krasnodar region and an oil depot in temporarily occupied Kerch."

"In addition, military logistics facilities were successfully struck, along with four radar stations belonging to S-400 systems and two Pantsir systems," he wrote.

Crimean governor Aksyonov had also announced that "Further decisions regarding the current situation in the republic's fuel market will be announced at a later date."

BBC has separately reported that Kiev "hit a logistics facility for oil transportation in Russia's Krasnodar region, which lies adjacent to Crimea across the Kerch Strait. Local authorities said one person had been killed on a passenger ferry."

Saturday saw a long-range Ukrainian drone attack on an oil refinery in Russia's Tyumen region, which lies over 1,200 miles from the front lines of fighting - a significant reach and first of the war. It demonstrates that Russian anti-air defenses have struggled to intercept small, low-flying UAVs. Hundreds were sent against Crimea on Sunday.