Munich-based German aircraft engine maker MTU Aero Engines has warned its employees against populism before a regional election in Bavaria, and consultants EY have issued their local staff with similar guidance. Though neither company mentioned the anti-immigration Alternative for Germany (AfD) in their internal memoranda, the messages highlight corporate concerns about the rise of the far-right and perceived threats to German political stability.

The AfD, which has campaigned in Bavaria with the slogan "our state, our homeland", is poised to surge into the regional assembly in Bavaria for the first time after Sunday's vote.

MTU told employees in a letter: "Populist slogans don't take our country forward, but rather targeted government action on the basis of our core values."

"Germany, and especially a strategically-orientated industry like ours, relies on stable political conditions," MTU directors added in the letter, which was posted on the company's intranet and a copy of which was seen by Reuters. The directors stressed they were not advising their employees which party to back, but urged them to vote "responsibly". Around half of MTU's 10,000 workers are based in Bavaria.

The AfD has established itself across Germany with anti-Islamic rhetoric and attacks on Chancellor Angela Merkel's migrant policy. This is a particularly hot topic in Bavaria, where most of the 1.5 million asylum seekers who have reached Germany in the past three years entered the country. The AfD's rise has eroded support for Merkel's allies in Bavaria, the Christian Social Union (CSU), who are set to lose the absolute majority with which they have controlled the southern state for most of the post-war period.

In Bavaria, support for the AfD - with whom the CSU has ruled out an alliance - stands at 10-14 percent, surveys show. After the Bavarian vote, the AfD is set to have seats in 15 of Germany's 16 state assemblies and it is likely to enter the remaining one, Hesse, after a state election there on Oct. 28.

In an email sent to employees on Thursday and obtained by Reuters, EY's Munich-based managing director in Germany, Hubert Barth, wrote: "Today, our liberal democracy is once again exposed to major attacks at home and from abroad."

Referring to the "landmark" elections in Bavaria and Hesse - home to the financial centre of Frankfurt - Barth added: "Our democracy is an important part of our economic success."

"I call on all colleagues to exercise their right to vote in order to strengthen the democratic and constitutional forces in our country," Barth concluded in his email, which was headed "a political statement".

The expected setback for the CSU risks widening divisions within Germany's crisis-prone national government, which depends on support from the Bavarian party.