KIEV: The central Shevchenkivskyi district of Ukraine's capital was rocked by blasts on Monday for the second time in a week during the city's busy morning hours, with Mayor Vitali Klitshchko saying several residential buildings were damaged.

Several blasts hit the district after 8 a.m. (0500 GMT), when many people rush to work or school, just over an hour after the first wave of explosions hit some residential buildings.

"Rescuers are on the site," Klitshchko said on the Telegram messaging service, adding that as a result of what he said was a drone attack, a fire also broke out in a non-residential building.

There was no immediate information on casualties.

Kiev's city administration said after the first wave of explosions that "critical infrastructure" was being attacked.

Shevchenkivskyi district, a busy hub with universities, student bars and restaurants, was hit by several explosions on Monday last week when Russia ordered the biggest aerial offensive against Ukrainian cities in retaliation for a blast on a bridge linking mainland Russia to Crimea. 

Andriy Yermak, head of the Ukrainian president's staff, said the latest attacks were carried out with so-called suicide drones.

"Russians think this will help them, but such actions are just their convulsions," Yermak said on Telegram.

Ukraine has reported a spate of Russian attacks with Iranian-made Shahed-136 drones in recent weeks. Iran denies supplying the drones to Russia, while the Kremlin has not commented.

Russia denies targeting civilians in what it calls its "special military operation" in Ukraine.