MIAMI (AFP) - Rescuers found a body on Wednesday (June 22) off Florida's Gulf Coast near where a father and his three teenage children went missing aboard a sailboat on Sunday, the Coast Guard said.

The unidentified body, wearing a life jacket, was found shortly after the Coast Guard located debris from what appeared to be a shipwreck, spokesman Nyx Cangemi told AFP.

Mr Ace Kimberly, 45, and his daughter Rebecca, 17, and sons Donny, 15, and Roger, 13, were last seen on Sunday morning near Englewood, around 130km south of Tampa, the Coast Guard said.

They left Sarasota, Florida earlier in the day aboard a 9m sailboat, heading south for Fort Myers earlier on Sunday.

Mr Kimberly later called his brother to report heavy seas, saying he saying he was attempting to survive with his children, the agency said.

The Coast Guard launched air and sea rescue crews to search for the missing family.

On Wednesday, an air crew found a tarp, four water bottles, six life jackets, a basketball, sneakers and a propane tank 33 miles off Florida's coast, the Coast Guard said during a news conference.

It also found a green kayak believed to belong to the missing family, the agency said on Twitter.

"We'll do everything we can for as long as we can," Coast Guard Captain Gregory Case said during the news conference. "It is a tough case."

The family's relatives are "terrified, as you can imagine", he added. "They're all feeling what we're all feeling, very anxious, upset and hoping for the best."

The Coast Guard did not receive a distress call from the boat and were alerted by Mr Kimberly's brother, Capt Case said.