This undated and unlocated handout picture released by the French national police shows Osnachi, 2 years and 4 months, who was kidnapped in Marseille on May 5, 2019, but found on Monday.

A two-year-old boy who was abducted in the French port city of Marseille has been found safe and sound and his kidnapper arrested, prosecutors said.

The toddler was recovered from a hotel in the city of Valence, some 200 kilometres from where he was snatched a few hours earlier on Sunday afternoon, Marseille prosecutor Xavier Tarabeux told AFP. 

The French alert system has been used more than 20 times since it was established in 2006

He said the alleged kidnapper, who has a criminal record, was arrested at the hotel.

The kidnapping had triggered the so-called "abduction alert" system, inspired by the Amber Alert child abduction system set up in the United States in 1996 after the kidnap and murder of a nine-year-old girl in Texas.

"It was the night watchman at the hotel who saw abduction alert on the television and called police," said Tarabeux.

The boy, named Osnachi, was snatched as his mother was attending a religious service in Marseille. The child "is fine" and will undergo medical examination, the prosecutor said.  

The French alert system has been used more than 20 times since it was established in 2006, and all the children were found safe and sound, all but two of them very quickly.

The last time it was triggered was in January when a father abducted his critically sick baby from a children's hospital in the southern city of Toulouse.

The child was found 24 hours after being kidnapped and was said to be in a good condition. 

The 33-year-old unemployed father and his elder brother were arrested.