The trailer for Harry Potter And The Chamber Of Secrets introduces a new character, Dobby the House Elf, who warns Harry of the danger of returning to Hogwarts for a second term.
Potter fans will also see Harry and his friend Ron in a flying Ford Anglia, swooping down on the Hogwarts Express school train.
A 30-second "teaser" from the trailer is already available on the internet.
The full-length trailer for the sequel will be shown in the UK from 12 July, when it will run exclusively with the Scooby-Doo film.
Harry Potter and The Chamber of Secrets is released in UK cinemas on 15 November.
The film, directed by Christopher Columbus, will reunite much of the cast of Harry Potter And The Philosopher's Stone, including Daniel Radcliffe, Rupert Grint and Emma Watson.
Kenneth Branagh also joins the team as the Professor of Defence Against the Dark Arts, Gilderoy Lockhart.
Columbus, who directed the first big screen adaptation of JK Rowling's successful wizard series, has reportedly decided that two is enough, and is keen to return to the US with his family.
There have been reports that Mexican film-maker Alfonso Cuaron, who wrote and directed erotic road movie Y Tu Mama Tambien, has been approached about taking over the third Potter movie, Harry Potter And The Prisoner Of Azkaban, due to open in 2004.
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