One of Ukraine's richest men and his family 'suffer horrific injuries in terrorist attack in heart of Monaco'

It later emerged that the device detonated at a foyer to a luxe apartment block called the Sun's Palace - as well as that a Ukrainian oligarch had been injured.

Vadim Ermolaev has been named across local media as one of the victims of the blast.

Mr Ermolaev is one of the embattled nation's richest men, and fled home after the start of the latest flare-up in fighting with Russia.

One of the other victims was his wife Anna, a source close to the investigation told local media, while his 13-year-old son is also believed to have been hurt.

The second victim was described as a woman in her 50s or 60s, with witnesses claiming they saw her as having "her feet missing" and "slumped over, covered in blood" following the blast.

The third victim is thought to be the 13-year-old - one of the couple's four children.

All three were said to have been standing at the entrance to building at the time the backpack blew up.

Lionel Beffre, a Monaco Government official, said there were "three victims in a critical condition", including Mr Ermolaev, a Ukrainian woman in "their 50s or 60s", and a 13-year-old.

Another witness described seeing a "little boy" at the bomb site "lying on the ground, covered in blood, with someone trying to help him".

CCTV images of the alleged bomber show a man wearing a black jacket and hat, and light pants.

Silvano Ippolito, who lives near the explosion, said he had thought it had come from a gas leak.

He claimed to have seen the woman and boy bloodied as he evacuated his building.

Marine Cotta, a woman who lives near the site of the explosion said she believed the explosion was a "fireworks display", only learning it was an attack on social media.

The Minister of the State of Monaco, Christophe Mirmand, said early signs indicated it was "likely an attack".

Mr Mirmand added: "This is the first time in history, to my knowledge, that such an act has occurred in the Principality."

Mr Ermolaev made his fortunes as a real estate developer in the Ukrainian city of Dnipro.

The businessman established the Alef Group, which handles his property portfolio and manufactures products ranging from apples to dental implants.

Police sources said authorities last night activated the Monaco "Red Plan".

The Red Plan is described as an action plan for Monegasque authorities where there are multiple people attacked.

Emergency services from over the border in France are responding to the incident.

This includes five fire engines and 14 firefighters from the Alpes-Maritimes fire and rescue department.

The Mayor of Nice, Eric Ciotti, said on social media: "The attack committed this evening is a tragedy for Monaco."

Mr Ermolaev is one of nearly 100 wealthy Ukrainians who left their home country for the picturesque tax haven as the war with Russia broke out.

He had earlier become a citizen of Cyprus in 2017, telling Forbes he needed "international protection" the Ukrainian judicial system did not provide.

The billionaire has four children, two boys and two girls, with his wife, who is a dentist and charity worker.

The family is said to have been living in luxury in the tiny Mediterranean country for the last few years - with Mr Ermolaev known for parking his Ukrainian-registered Bentley outside the Monte Carlo Casino Square.

He also owned a superyacht flying the Ukrainian flag, as well as a high-security villa in nearby Saint-Jean-Cap-Ferrat.