According to Reuters:
Reporters were taken aboard the plane to examine the cargo, which included a rubber dinghy, military uniforms, wire cutters, armour, compasses and other military hardware, said chief police spokesman Assistant Commissioner Wayne Bvudzijena.
and
Footage on state television showed a white plane with the figure N4610 printed on the body. Several army personnel were shown sifting through equipment including what appeared to be army boots, communication radios and sleeping bags.
U.S. Federal Aviation Administration records show N4610 to be a 727 plane registered to Dodson Aviation based in Ottawa, Kansas. Dodson Aviation said it sold the plane in question about a week ago to an African company called Logo.
I would really hate to be stuck in a Zimboland jail..whatever these "mercenaries" might have done, I hope they are treated fairly.