Ukrainian officials said the number injured in the attack has risen from 117 to 144.

People had been on their way to church to celebrate a religious holiday when the strike hit, Ukraine interior's ministry has said.

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In his nightly video address, delivered at the end of a visit to Sweden, Ukraine's President Volodymyr Zelenskyy said: "I am sure our soldiers will give a response to Russia for this terrorist attack.

"A notable response."

He said that of the 144 people injured, 15 were children, and named the girl killed as Sofia. Fifteen others were police officers.

Earlier, Mr Zelenskyy posted on Telegram: "A Russian missile hit right in the centre of the city, in our Chernihiv. A square, the polytechnic university, a theatre.

"An ordinary Saturday, which Russia turned into a day of pain and loss."

A short video accompanying Mr Zelenskyy's post showed debris scattered across a square in front of the regional drama theatre, where parked cars were heavily damaged.

The video also briefly showed a body slouched inside a car.

The interior ministry said the roof of the drama theatre had been destroyed in the strike.

Oleksandr Lomako, the city's mayor, wrote on Telegram: "This strike is another war crime by the occupiers against the civilian population.

"This is a very quiet centre, many people and children walk here at lunchtime in beautiful weather."

He also declared a national period of mourning until 21 August.

Chernihiv is a city of leafy boulevards and centuries-old churches about 90 miles (145km) north of the capital Kyiv.

Russia has attacked Ukrainian cities far from the frontline with missiles and drones as part of the invasion it launched in February last year.

Kyiv's air force said early on Saturday the Ukrainian military had shot down 15 out of 17 Iranian-made Shahed drones
launched by Moscow in an overnight strike.

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It came before Mr Zelenskyy said Ukraine had started discussions with Sweden about the possibility of receiving Gripen fighter jets.

The Ukrainian president was in Sweden for a series of talks - his first visit since Russia launched its invasion in February 2022.

He arrived before Russia's defence ministry said it had destroyed a Ukrainian drone over Belgorod.

The southern region, which sits close to Russia's border with Ukraine, has come under numerous attacks in recent months.

Drones and missiles have often been used to target the area, but Kyiv has not accepted responsibility for the strikes.

Russia claimed to have downed a drone there just two days ago.