Blasts heard in Kyiv during ballistic missile alert: AFP

A series of explosions rang out in Kyiv shortly after midnight on Thursday, an AFP journalist said, after a Ukrainian air force alert reported the approach of several ballistic missiles.

There were a number of bright flashes in the sky over Ukraine's capital, followed by half a dozen detonations, they said.

The attack came a few hours after European Commission President Ursula von der Leyen visited to boost defence ties.

Kyiv Mayor Vitali Klitschko wrote on social media that a warehouse was hit while "missile debris fell on non-residential buildings".

At the same time, Kharkiv, the main city in northeast Ukraine, was hit by combat drones, its mayor said.

Kyiv has been regularly targeted by Russian strikes using ballistic missiles since last month. The weapons are fast and more difficult to intercept.

During bombardments, missiles are fired in successive salvoes and blasts occur in quick succession.

Kyiv is suffering in particular from a shortage of PAC-3 missiles for its US-designed Patriot systems, which are essential for intercepting ballistic projectiles.

US President Donald Trump announced last week that he intended to authorise Ukraine to produce missiles for Patriot defence systems.

His Ukrainian counterpart, Volodymyr Zelensky, said on Wednesday that production could begin by the end of this year, to strengthen the country's defences against Russian ballistic strikes.