Voters in two former East German states go to the polls Sunday in elections expected to deal a blow to Chancellor Olaf Scholz's government and deliver big gains for the far-right AfD.

The polls in Thuringia and Saxony come just over a week after three people were killed in a suspected Islamist attack, which has fuelled a bitter debate over immigration in Germany.

Opinion polls have the anti-immigration Alternative for Germany (AfD) ahead in Thuringia and a close second in Saxony, while also predicting a strong showing for the upstart, far-left BSW.

The two parties have found a receptive audience in the eastern states for their criticism of the government in Berlin and of military aid to Ukraine.

An election victory for the AfD would be a landmark in Germany's post-war history and represent a rebuke for Scholz, ahead of national elections in 2025.

In both states, Scholz's Social Democrats are polling around six percent, while their coalition partners, the Greens and the liberal FDP, lag even further behind.

But even if the AfD does come out on top in the elections, it is unlikely to come to power because other parties have ruled out working with the far right to form a government.

Voting in both regional elections will start at 8:00 AM local time (0600 GMT), with polling stations closing at 6:00 PM.

Far-right rise

The ballot-counting will start immediately after voting ends, with the first exit polls expected shortly after.

Created in 2013 as an anti-euro group before morphing into an anti-immigration party, the AfD has capitalised on the fractious three-way coalition in Berlin to rise in the polls.

In June's EU Parliament elections, the party scored a record 15.9 percent overall and did especially well in eastern Germany, where it emerged as the biggest force.

Saxony is the most populous of the former East German states and has been a conservative stronghold since reunification. 

Thuringia meanwhile is more rural and the only state currently led by far-left Die Linke, a successor of East Germany's ruling communist party.

A third former East German state, Brandenburg, is also due to hold an election later in September, where polls have the AfD ahead on around 24 percent.

The picture in each state is slightly different but "in any case, it is clear that the AfD will unite a very strong number of votes behind it", Marianne Kneuer, a professor of politics at the Dresden University of Technology (TU Dresden), told AFP.

New challenger

The AfD has found stronger support in the east where more voters "identify with its nationalist and authoritarian positions" and many are dissatisfied with the mainstream parties, according to Kneuer.

The same currents have fed support for BSW, founded in January by the firebrand politician Sahra Wagenknecht after she quit Die Linke.

Like the AfD, Wagenknecht and her party have made hay with a dovish stance towards Russia and calls for a radical crackdown on immigration.

BSW scored an immediate success in June's European elections, hauling in some six percent of the German vote, and is polling a strong third in Saxony and Thuringia.

Other parties' refusal to work with the AfD leaves BSW as potentially the kingmaker in Thuringia and Saxony, despite serious policy disagreements with potential partners -- especially on Ukraine. 

The run-up to polling day in Saxony and Thuringia has however been dominated by outcry over immigration stirred up by the deadly stabbing in the western city of Solingen.

The alleged attacker, a 26-year-old Syrian man with suspected links to the Islamic State group, was slated for deportation but evaded attempts by authorities to remove him. 

The government has sought to respond to the alarm caused by the incident by announcing stricter knife controls and rules for migrants in Germany illegally.

The conservative CDU, which holds hopes of winning both elections, has said the initial measures do not go far enough and urged a halt to arrivals from Syria and Afghanistan.

by Pauline Curtet with Sebastien Ash in Berlin, AFP