A Ukrainian F-16 pilot was killed while repelling the most intense Russian air assault since the start of the war, President Volodymyr Zelenskyy said Sunday.

An air force statement said that the pilot, a lieutenant colonel, did all he could to guide his stricken plane away from residential areas, but failed to eject in time.

The pilot, born in 1993, reportedly downed seven targets before being hit.

"Unfortunately, we have suffered another painful loss," the air force statement said.

Zelenskyy expressed his sympathies to the pilot's relatives.

According to the air force report, Russia launched 537 drones, missiles and cruise missiles at Ukrainian territory overnight, causing injuries and severe damage to civilian infrastructure.

Ukrainian media said the number was the highest since the full-scale Russian invasion in February 2022.

A residential block was hit in Smila, a city in the Cherkasy region to the south-east of Kyiv. A child was injured, the local authorities reported.

Zelenskyy repeated demands for greater international pressure on Russian President Vladimir Putin to end the war.

Last week, Russia attacked with 114 missiles, more than 1,270 drones and almost 1,100 glide bombs, he said.

"(Russian President Vladimir) Putin long ago decided to continue fighting, disregarding the appeals for peace from around the world," Zelenskyy posted on Telegram.

He also stressed that Ukraine had to boost its air defenses and said it was willing to buy U.S. air defense systems.

The loss of pilots trained in the West on U.S. F-16 fighter jets is seen as highly significant for Ukraine. Losses from F-16 squadrons have been relatively rare to date.