Adventure specialist Kumuka which ceased trading last week has apologised to passengers booked to travel.
It said all tours leaving up until yesterday would go ahead but anyone booked after this date would need to re-book with another operator.
Administrators have been called in and rivals Dragoman and Tucan have offered discounted rescue packages.
The Surrey-based overland truck operator, which covered Africa, Asia, Antartica, Latin America, North America, Europe and the Middle East, was established in 1983 and claimed to carry over 12,000 clients a year.
Its website said: "We are sorry to announce that Kumuka has ceased trading. We apologise unreservedly to all Kumuka passengers and we are working hard to respond to all enquiries."
It said Kumuka holidays, which traded all over the world, is ATOL protected for customers who book and pay in the UK. Passengers should contact the CAA.
The CAA could not say how many forward bookings there were but added that the operator was only licensed to sell 500 ATOL-protected holidays annually.
By Diane Evans
Monday, July 23, 2012