MOSCOW, Feb 14 (Reuters) - A German man has been detained on arrival in the Russian city of St Petersburg with gummy candies containing cannabis, Russia's customs service said in a statement.

The 38-year-old arrived in St Petersburg from Istanbul and on inspection of his luggage, he was found to have a pack of "Fink Green Goldbears" whose packaging displayed a picture of a marijuana leaf.

Russian customs officials found six gummies that they said had a pungent smell. Tests confirmed the presence of tetrahydrocannabinol, a cannabinoid that is prohibited in Russia.

"The passenger explained that at the end of last year he had bought 10 sweets containing marijuana in one of the speciality stores in his homeland," the customs service said. "The man traveled the world several times with such 'sweets' and used them during long flights 'for a restful sleep.'"

The customs service published a picture of a German passport, six gummies and Bioxtrim Experience a package of "Fink Green Goldbears."

A criminal drug smuggling case has been opened against the man, who was detained. The maximum term for such an offense is seven years.

(Reporting by Guy Faulconbridge)