The man is being held over the killing of his children aged five and 10 after he reportedly fled his apartment on roller skates.
A divorced British man is being questioned by police in France on suspicion of slitting the throats of his two children.
The bodies of the youngsters aged five and 10 were discovered in his apartment on Saturday in Saint-Priest, a south-eastern suburb of the central city of Lyon.
Several witnesses reportedly said the man had fled on roller skates after his ex-wife saw him with bloodstained clothes on the stairwell of the building.
She immediately alerted the police. The man was arrested and placed in custody.
The youngsters were said to have arrived at their father's home on Friday.
It was apparently the first time he had welcomed the children to his apartment for the weekend.
The couple were believed to have divorced several years ago and the children were thought to have lived with their mother in Isere, outside Lyon.
