Austrian police have made an appeal to the public for help over a tourist thought to be German languishing in the country for the past seven weeks who has lost his memory and has no identification papers.

All police know is that the man arrived in the town of Lindau on Lake Constance by train on November 19 wearing hiking gear, went to the tourist office and walked to nearby Bregenz.

Since then the man, aged around 50 and who on account of his "High German" accent is strongly believed to be a German, cannot remember his name or where he comes from, police said.

"We have had 10 leads so far, and we will examine them all," a police spokesman told Sunday's edition of the Kronen-Zeitung daily. "He has good days and bad days."