Sydney  - The parents of German backpacker Jan-Christian Bielenberg, who has been missing on Australia's west coast for more than a week, Friday appealed for help in finding him.

Bielenberg, 20, was last seen on closed-circuit television leaving his Bunbury hostel July 30 after realizing he had locked himself out of his room.

Wilhelm and Ursula Bielenberg made the televised appeal after their arrival in Bunbury from their home in Alfeld, Lower Saxony, Germany.

"As we know him, he is a strong and self-confident person, he easily makes friends," Wilhelm Bielenberg told Australia's AAP news agency. "He doesn't have all his clothes, or his passport, so we are worried."

Western Australian Police spokeswoman Ros Weatherall said Bielenberg had last contacted his family just hours before he disappeared.

He had a flight to Germany booked for August 13 but told his family he was thinking of extending his stay.

Weatherall said money had not been drawn from his bank account since he went missing. (dpa)