FILE PHOTO: A partly visible election campaign poster of Germany's anti-immigration party Alternative fuer Deutschland AfD reads "vote AfD" as Angela Merkel, German Chancellor and leader of the Christian Democratic Union party CDU, appears partially on a changing advertising board in Bonn, Germany, September 14, 2017. REUTERS/Wolfgang Rattay/File Photo

BERLIN (Reuters) - Support for Chancellor Angela Merkel’s conservative bloc has slumped to a record low after a bruising internal row over migration policy, with support for the far-right Alternative for Germany (AfD) hitting a record high, a poll showed on Thursday.

The ARD DeutschlandTrend survey put support for Merkel’s conservative alliance - her Christian Democratic Union (CDU) and its Bavarian allies, the Christian Social Union (CSU) - at 29 percent, down one point from the beginning of July.

Merkel, who has led Germany since 2005, only narrowly averted the collapse of her coalition government last month after a row between the CDU and the CSU over immigration policy.

The conservative sister parties rule in a grand coalition with the left-leaning Social Democratic Party (SPD).

The anti-immigration AfD gained one point in the ARD DeutschlandTrend survey, conducted by pollster Infratest Dimap, to a record high of 17 percent.

In last September’s federal election, the CDU/CSU bloc won 32.9 percent of the vote and the AfD surged into the national parliament for the first time with 12.6 percent, making it the third largest party. The SPD came second with 20.5 percent.

The survey put support for the SPD at 18 percent, unchanged from early July. Infratest Dimap polled 1,508 voters across Germany from Monday to Wednesday of this week.

The survey also showed that two SPD politicians - Foreign Minister Heiko Maas and Finance Minister Olaf Scholz - were respectively Germany’s most popular and second most popular politicians. Merkel came third.

Support for the far-left Left party was unchanged at 9 percent, the poll showed. The business-friendly Free Democrats (FDP) were down one point at 7 percent and the ecologist Greens up one point at 15 percent.