Frauke Petry, co-chief of the nationalist Alternative for Germany party, on Monday declared she would not join her party's parliamentary group amid a bitter dispute with more hardline colleagues.

"I decided after careful reflection that I will not sit with the (AfD) parliamentary group" in the Bundestag, Petry told a press conference alongside other key figures in the party before abruptly leaving the room.

Petry won a direct mandate in Sunday's election and said she would still serve as an MP