Supporters of Turkish President Recep Tayyip Erdogan in Germany have been trying to intimidate voters ahead of the country's crunch election, politicians and voters said on Tuesday.

In Berlin's Neukoelln district, a local chapter of the opposition CHP party has been laying on buses to carry voters across the city to vote in the Turkish consulate.

Ercan Yaprak, co-leader of the local chapter, said he had seen groups of pro-Erdogan demonstrators at the consulate.

"We are being provoked. But we won't rise to it," Yaprak told AFP.

"If they are waiting in the consulate for us to say something back, we won't do that. We don't want a fight."

As voters gathered at the CHP bus station on Tuesday, a car drove past blasting pro-Erdogan music.

Katresu Ergez, 29, a Turkish-German citizen among those waiting to board, had already gone to the consulate last week to accompany one of her friends to vote.

"You get insulted on the way in," she said. 

"If you don't wear a headscarf or you wear more modern clothes, you are directly labelled as anti-Erdogan and insulted."

Ergez said she had also seen abuse from Erdogan supporters on social media.

"You often get insults, you are called a terrorist and many other things," she said.

- 'Blatant attempt' -

There are roughly 1.5 million registered Turkish voters living in Germany, the largest diaspora participating in Turkey's most pivotal election in decades.

They have been voting since April 27, with polling stations due to close on Tuesday evening.

Around one in two voters in Germany went to the ballot during the last elections in 2018, and support then for Erdogan was stronger in Europe's biggest economy than in Turkey itself.

With polls showing Erdogan, 69, locked in a tight battle with secular rival Kemal Kilicdaroglu and his powerful alliance of six parties that span Turkey's cultural and political divide, the pressure is on for every vote.

Erdogan backers have been pressing Turks in Germany "with methods that are not acceptable", according to Herbert Reul, the interior minister of North Rhine-Westphalia state.

"There is a blatant attempt to influence opinion-forming or even to put people under pressure," Reul told the ZDF broadcaster in an interview to be aired on Tuesday evening.

Supporters of Erdogan and his AKP party have often stirred controversy in Germany.

Earlier this year, an AKP politician in Neuss threatened Turkish opposition politicians in exile in Germany, saying: "We beat them up in Turkey and now we'll beat them up in Germany." 

Such statements must be countered, Reul said.

"If any politician thinks they can continue the Turkish election campaign here, then we won't allow it."

fec/hmn/imm