GERMAN Chancellor Angela Merkel's conservative Christian Democrats Union (CDU) has fallen to third place in a state election behind the centre-left Social Democrats (SPD) and anti-immigrant Alternative for Germany (AfD) party, exit polls show.

The AfD campaigned hard against the Chancellor's policies on refugees and obtained about 21 per cent of the vote in its first bid for seats in the regional Parliament of Mecklenburg-Vorpommern, according to exit polls shortly after voting ended.

Ms Merkel's Christian Democratic Union, meanwhile, garnered just 19 per cent in its worst ever showing in the north-eastern state, while the Social Democrats maintained top place with about 30 per cent.

"This isn't pretty for us," said Michael Grosse-Groehmer, one of Ms Merkel's top deputies in Parliament in Berlin in a ZDF TV interview.

"Those who voted for the AfD were sending a message of protest."

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