No details of the suspect were given.
The Hermitage said at the end of July that 221 items, including icons, medieval and 19th-century jewelry, silverware and enamels, had been stolen from its Russian art section. The theft had been uncovered during a routine check.
Earlier, police arrested an antiques dealer and the husband and son of a Hermitage custodian in charge of the missing objects, who died from a heart attack when the inventory began.
Sixteen of the items stolen from one of the world's richest art collections have been recovered so far, including a gold-and-silver cross and two icons.
The large-scale theft of artwork from the Hermitage and the disappearance of a famous architect's drawings, worth several million dollars, from a Russian state archive, which had been announced earlier this week, prompted President Vladimir Putin to order inventories of museum collections nationwide.
