Ukrainian President Volodymyr Zelensky said Friday that Russian air superiority was “stopping” Kyiv’s counteroffensive, complaining of the slow rate of both Western arms deliveries and sanctions on Russia.

Ukrainian officials have expressed frustration at criticism that Ukraine’s counteroffensive has been too slow.

“If we are not in the sky and Russia is, they stop us from the sky. They stop our counteroffensive,” Zelensky said, calling for more “powerful and long-range” weapons.

Kyiv has repeatedly asked for planes to battle Russia’s invasion, but many of its Western allies have been hesitant.

Ukraine has for weeks complained about the slow process of getting US-made F16s to improve its Soviet-era fleet.

“When some partners say: so what about the counteroffensive, when will the next step be? My answer: today, our steps are certainly faster than the new sanctions packages,” said Zelensky.

Arms delivers to Kyiv and new rounds of sanctions on Russia were becoming “complicated and slower”, he added.

Ukraine relied on Western arms deliveries to launch its long-anticipated counter-offensive this summer.

It has acknowledged the advance has been slow due to heavily mined territory.

But Kyiv has also reported some success recently.

It declared a strategic victory last week with the capture of the southern village of Robotyne, which it said would pave the way for forces to push deeper towards Moscow-annexed Crimea.