A businessman who found his warehouse's security guard asleep in his car on Monday morning thinks robbers used a forklift to steal 9,000 mobile phones.

Miami Herald reported Daniel Kaufman had hired a 24-hour security firm and installed digital surveillance cameras and an alarm system to protect his mobile phone and parts distribution business.

Despite those measures, Kaufman arrived at his Deerfield Beach warehouse to find a three foot by three foot (0.914 metre by 0.914 metre) hole in a metal bay door at the rear and USD1.5 million in mobile phones missing.

He guessed a forklift was used to carry the boxes of mobile phones out through the bay door opening.

A USD50,000 reward is offered for information leading to the robbers' arrest. Call CrimeStoppers at +1 954 493 TIPS.