Police in Cambodia were on Sunday investigating how five bodies, thought to be those of a Frenchman and his four children who went missing last year, ended up in a car dumped in a pond behind the French family's home.

Laurent Vallier, 42, and his children aged 2 to 9 disappeared from their home in Kompong Speu province near the capital, Phnom Penh, in September and the French Embassy said it had alerted authorities in November that they were missing.

The embassy said in a statement it had been informed of the discovery of the remains but that, because of the state of the corpses, it is impossible to confirm that these are the bodies of Monsieur Vallier and his children.

Police said one skull had been found inside an open suitcase, having apparently floated in there after the car was submerged.

Relatives of Vallier's Cambodian wife, who died during childbirth, held a religious ceremony for the dead on Sunday.

Neighbours were shocked to learn of the grim discovery.

We just saw him taking his children to school every day and then they just disappeared, said Chuob Srey, 43. We thought they'd gone on holiday.

Police would not comment further because of the preliminary stage of the inquiry. We don't know whether this was a robbery or a murder. Just let our expert team work on it, said district Police Chief Touch Heang.

(Reporting by Prak Chan Thul; Editing by Alan Raybould and Sanjeev Miglani)