UPDATE 1-German antitrust watchdog launches new proceedings against Amazon

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BERLIN, May 18 (Reuters) - Germany's antitrust watchdog said on Tuesday it has launched a new investigation into whether U.S. ecommerce giant Amazon is exploiting its market dominance.

"In a first step, we are looking at whether Amazon is of outstanding, cross-market importance for competition," the Federal Cartel Office said in a statement.

Should it find that such a marketing position exists, new rules for digital companies would allow it to prohibit any anti-competitive behaviour at an earlier stage, the watchdog said.

Changes to Germany's antitrust laws for digital corporations, which came into effect earlier this year, give the Cartel Office more power in identifying and prohibiting some companies' dominant positions.

The Bonn-based authority has already initiated proceedings against Amazon's price control mechanisms and relationships with third-party traders selling on its site.

A spokesman for Amazon said it could not comment on ongoing proceedings. (Reporting by Kirsti Knolle Editing by Caroline Copley)