A Texas travel agency which organises clothing-optional holidays, is to run what it claims is the world's first nude flight.

Houston-based Castaways Travel says sex won't be allowed on the flight from Miami to Cancun in Mexico.

It has chartered a Boeing 727 for up to 170 passengers for the May 3 flight to the El Dorado Resort & Spa.

The crew will be professionally dressed, and passengers must be fully-clothed for check-in and takeoff.

Company owner, James Bailey, said more than half the seats on the flight and rooms in the resort have already been booked, reports the Miami Herald.

He told the newspaper: ''Inappropriate behaviour is not condoned. This is not a Mile High Club, not a bunch of groupies or anything. It's just a fun flight."

Only when the plane has reached its cruising altitude can the passengers strip off.

The Federal Aviation Administration said: ''We have no regulations pertaining to nudity on board an aircraft. It's not a safety issue."