Ukrainian President Volodymyr Zelenskyy says his country's security service has attacked more than 30 Russian oil facilities in a special operation.

Ukraine is believed to be carrying out intermittent attacks on oil facilities across Russia with drones and missiles to undermine the refueling capability of Russian troops.

In a speech on Monday to personnel of the Security Service of Ukraine, Zelenskyy praised the special operation, saying the agency hit oil refineries and storage facilities.

Zelenskyy added, "For the SSU drones, a distance of 1,500 kilometers is no longer a problem." He said the successes of the armed forces and the intelligence body are "very significant" in bringing about "a just end" to the war for Ukraine.

Kyrylo Budanov, the intelligence chief at Ukraine's defense ministry, said in a US media interview released on Sunday that the supply of munitions from the West has accelerated compared with several months ago.

However, he noted that Ukraine needs huge amounts of weapons, and that the situation on the frontlines is extremely harsh.

Budanov said he expects current conditions to continue for at least another month.