The NYPD is working with the French Embassy to find a 21-year-old tourist who went missing in the city while he was on vacation with his family, authorities said Friday.

Arthur Astie had been in the city for about a week with his parents and sister before he went missing May 4 in the Bronx, police said. Authorities say the man, whose nickname is Ubu, was trying to catch a train to Harlem, where his family was staying, but hopped on the wrong train and got lost in the Bronx.

He was last seen heading back underground to try to get on the right train, authorities say.

Astie has no known friends in New York and speaks very poor English, police said. He's described as being about 5 feet 9 inches tall with blue eyes and a slim build.

Police released a photo of the man (above). Anyone with information on his whereabouts is asked to call the NYPD.