A manhunt is under way in southern France after a parcel bomb exploded at a residential building in neighbouring Monaco, injuring wealthy Ukrainian businessman Vadym Yermolaiev and two others.

Two of the injured are in a critical condition in hospital in the French city of Nice, Monaco public prosecutor Stéphane Thibault said, adding that a woman was most seriously hurt.

He said authorities were searching for a single suspect and the incident was being treated as attempted murder, not as a terrorist attack.

Ukraine’s foreign ministry said its embassy in France was in touch with Monaco’s authorities and was working to officially identify those reported injured in the blast.

The blast occurred shortly before 21:00 (19:00 GMT) at an apartment building on Rue Révérend Père Louis Frolla, near the border with France.

Monaco’s government said the explosion had been caused by a parcel bomb, while the head of Monaco’s government, Christophe Mirmand, told AFP news agency the explosive device had appeared to contain bolts and pellets.

Thibault said four other people had been treated by emergency services – one for shock and three for cuts from debris from nearby shop windows as a result of the blast.

Yesterday, Mirmand told French broadcaster BFM TV the suspect appeared to have left for France.

The Monaco government has said a suspect was seen on a video surveillance system fleeing towards the French commune of Beausoleil on foot after the explosion, where a major police effort to find them is now taking place.

Video surveillance images of the moments before the attack showed a man dropping a backpack in the lobby of a building shortly before the explosion, French newspaper Le Figaro reported.

More than 100 police and emergency personnel were deployed to the scene of the blast on Monday evening.