"Many Germans who didn't go on holiday last year are booking especially early this year," Sebastian Ebel, head of TUI Germany, said in a statement on Thursday.

Early bookings are good for tour operators' earnings because it makes it less likely for them to have to cut prices at the last minute to fill spaces.

Credit Suisse downgraded TUI on Wednesday to "underperform" from "outperform", flagging a tough outlook for its two largest markets - the UK and Germany, accounting for 33 percent and 26 percent of sales, respectively.

Last year saw European tourists avoid attack-hit Turkey and Egypt in favour of destinations in the western Mediterranean such as Spain, forcing tour operators and airlines to shift capacity.

Greece has replaced Turkey as the second most popular destination for Germans, TUI Germany said, and summer bookings for the country are currently 41 percent above where they were a year ago.

Spain, Italy, the Canary Islands and Croatia are also experiencing growth in bookings of over 10 percent, TUI Germany said.

The number of visitors to Spain hit a new record in 2016 for a fourth consecutive year, the government said on Thursday.

Germany is the world's third largest spender on foreign travel behind China and the United States.

(Reporting by Victoria Bryan; Editing by Greg Mahlich and Alexandra Hudson)