A huge Lego sculpture that mysteriously appeared this week on a Florida beach will remain in police custody for 90 days while investigators try to figure out who it belongs to, according to authorities.

The more than eight-foot-tall (2.5-meter) Lego Man weighing about 100 pounds (45 kilos) turned up on the sands of Siesta Key beach off Florida's Gulf coast on Tuesday, but no one has claimed responsibility for putting it there.

"The Sheriff’s Office is obligated to take and retain custody of the sculpture for a period of 90 days, just like all other lost and found property under this statute," the Sarasota County Sheriff's Office said in a statement.

"During this time, a determination will be made as to who has the best legal claim to it."

A swimmer first reported the existence of the green, yellow and red sculpture, which says "No Real Than You Are" on the front, and "Ego Leonard" on the back.

The Danish manufacturer of the wildly popular brick-building toys -- which opened the largest Legoland in the world in Orlando, Florida earlier this month -- has denied any involvement in the incident.

The Sarasota sheriff's office said it was "looking into the possibility of the sculpture being securely displayed so that it could be enjoyed by the community; however, the obligation to ensure its safekeeping takes priority."