Voting has opened in Germany's federal elections, with Chancellor Angela Merkel tipped to retain power, the BBC reported.

She is seeking a fourth term in office and to keep her Christian Democrat party's (CDU) status as the largest presence in Germany's Bundestag.

The CDU's coalition partner, the SPD, is its main opponent. The right-wing AfD is likely to gain seats in parliament for the first time.

Polling stations opened at 08:00 local time (06:00 GMT) and close at 18:00.