Three people have been seriously injured after a makeshift bomb detonated outside a residential building in Monaco.

Police have launched a manhunt to find the suspect, but it is believed he may have fled across the border to France.

Surveillance footage appeared to show him travelling on foot into the neighbouring French town of Beausoleil.

Local media reports suggest that a Ukrainian construction magnate and his family were among those hurt.

He has been named as Vadym Iermolaiev, with Ukrainian media claiming he has previously been targeted with sanctions because of his ties to Russia.

Two of the victims have suffered life-threatening injuries, with Monaco's leader Prince Albert II describing the explosion as an "odious act".

One of those in hospital is a child.

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Detectives across both countries are now investigating, but the attacker's motive is unclear at this stage.

Monaco's minister of state Christophe Mirmand told BFM TV: "No event of this nature has ever ‌happened in the principality before."

CCTV footage from the moments before the attack appeared to show a man leaving a backpack at the building's entrance shortly before the blast.

Eric Ciotti, the right-wing mayor of nearby Nice, described the explosion as "a tragedy for Monaco".

It happened in the centre of the tax-free microstate on the French Riviera, which is known as a haven for billionaires and their luxury yachts.