Osaka prefectural police dive into the inner moat of Osaka Castle to check for suspicious objects. (Kazushige Kobayashi)

OSAKA--In the tight security measures leading up to the Group of 20 summit here, even the inner moat of Osaka Castle located in Osaka's Chuo Ward is feeling the ripple effect.

Osaka prefectural police divers were checking the moat on June 24 for explosives, ahead of the June 28-29 summit.

About 30 members from Osaka prefectural police including riot police joined the search. The divers, wearing air tanks, jumped into the water and checked the stone wall and bridge piers of the castle while closely communicating with other officers in rubber rafts.

No suspicious objects were found and police finished the search after shouting “Clear!”

Located near the castle is the Osaka Geihinkan reception hall, a candidate site for a banquet where world leaders will be welcomed.

“It (the G-20 summit) is about to enter the key stage," a police official said. "We want to prepare for it with full security.”