Ukrainian defence forces said they shot down more than 20 drones during a fresh wave of Russian air attacks on Kyiv early Tuesday which killed at least one person and injured four others when their apartment building was hit and caught fire.

Kyiv's military administration said the latest attack involved only Iranian-made Shahed drones, and no missiles as has been the case in most previous raids.

"A massive attack!" Kyiv Mayor Vitali Klitschko said on the Telegram messaging app. "Do not leave shelters."

One person died and four were injured when debris from a destroyed Russian projectile hit a high-rise apartment building sparking a fire, Ukrainian officials said.

Two upper floors of the building were destroyed and there could still be people under the rubble, Kyiv's military administration officials said on the Telegram messaging app.

Photos from Kyiv officials and Reuters witnesses showed flames engulfing the top floors of the building and smoke rising from the roof.

"The attack was massive, came from different directions, in several waves," Serhiy Popko, head of Kyiv's military administration, said on the Telegram.

Debris hit several other districts of the capital including the historic Podil and Pecherskyi neighbourhoods. It was not immediately known how many drones Russia launched and there was no immediate comment from Moscow.

Russia has repeatedly attacked the Ukrainian capital in May using a combination of drones and missiles, mostly at night, in an apparent attempt to undermine Ukrainians' will to fight after more than 15 months of war.

Tuesday's strikes were Russia's 17th air assault on the capital this month and came after the city was attacked twice on Monday, including an unusual daytime strike.

In a rare acknowledgement of damage to a military "target", Ukraine said a runway was damaged and five aircraft were taken out of service on Monday in western Khmelnitskiy region.

Russian state-owned news agency RIA cited the defence ministry as saying more than one air base had been hit. There was no confirmation from Ukraine of damage to other air bases.

Ukrainian officials said most of the drones and missiles fired on Sunday and Monday had been shot down and President Volodymyr Zelenskiy praised U.S.-supplied Patriot anti-missile defences.

"When Patriots in the hands of Ukrainians ensure a 100% interception rate of any Russian missile, terror will be defeated," Zelenskiy said in his nightly video address on Monday.

Psychological warfare

The air attacks come as Ukraine prepares a counter-offensive backed with Western weapons to try to drive Russian occupiers out of territory seized since Moscow launched what it calls its "special military operation" in February 2022.

"With these constant attacks, the enemy seeks to keep the civilian population in deep psychological tension," said Serhiy Popko, the head of Kyiv's military administration.

On the eastern frontlines, Russian paratroops and motorised units were replacing Wagner mercenary units in the eastern city of Bakhmut, according to Serhiy Cherevatyi, a spokesperson for the eastern group of Ukrainian Forces.

Wagner began handing over positions to regular troops this week after declaring full control of Bakhmut following the longest and bloodiest battle of the war.

Moscow said it invaded Ukraine to "denazify" its neighbour and protect Russian speakers. Western opponents say the invasion is an imperialist land grab in which tens of thousands have been killed, millions uprooted and cities reduced to ruins.

Russia says it is open to resuming stalled peace talks with Kyiv and has welcomed mediation efforts from Brazil and China.

But a top aide to Zelenskiy said Kyiv's peace plan, envisaging the full withdrawal of Russian troops, was the only way to end the war.

"There cannot be a Brazilian peace plan, a Chinese peace plan, a South African peace plan when you are talking about the war in Ukraine," chief diplomatic adviser Ihor Zhovkva told Reuters in an interview late on Friday.

Call for a DMZ

Another Zelenskiy aide, Mykhailo Podolyak, wrote on Twitter that any post-war settlement should include a demilitarised zone of 100-120 km (62-75 miles) inside Russia along the border.

The European Union's top diplomat, Josep Borrell, said he believed Russia would not want to negotiate while it was still trying to win the war.

Ukraine's military said an attack on Odesa port had caused a fire and damaged infrastructure but did not specify whether the damage threatened grain exports.

Ukraine is an key global grain supplier and the port is vital for shipping. It is also one of three countries in a U.N.-brokered deal on the safe export of grain via the Black Sea.

Russia said on Monday the grain deal would no longer be operational unless a U.N. agreement with Moscow to overcome obstacles to Russian grain and fertiliser exports was fulfilled.

This month, Moscow reluctantly agreed to extend the grain deal until July 17.