Maximilian Krah, who is a top candidate for the Alternative for Germany party (AfD) for the June vote, said he would dismiss his aide, Jian G, after he was arrested on Monday.

Prosecutors claim Jian G worked for Chinese intelligence and passed on information about negotiations and decisions in the European Parliament in January.

He is also accused of spying on Chinese dissidents based in Germany.

The Chinese-German national has worked for Krah since 2019.

His arrest at his home in Dresden earlier this week cast fresh scrutiny on the AfD, which has previously been criticised for being too friendly to Russia.

Mr Krah has said he knew nothing about his assistant's alleged espionage but said his office would look into everything he had worked on.

"I am very much interested in clearing this up, and will endeavour to find out what exactly he is accused of," Mr Krah told journalists in Berlin, adding: "The election campaign is, of course, being terribly overshadowed by this matter."

The investigation is the latest controversy facing the far-right party which sparked national protests earlier in the year after some of its members attended a meeting where the mass deportation of immigrants and asylum seekers was discussed.

In an unrelated case, one of its leaders is also on trial for allegedly using Nazi language - a charge he denies.

News of Jian G's arrest came a day after three Germans suspected of spying for China and arranging to transfer information on technology with potential military uses were arrested in a separate investigation.

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On Wednesday, the German Chancellor called the spying allegations "very concerning" and urged more action to root out such cases.

Olaf Scholz was speaking at a joint news conference with British Prime Minister Rishi Sunak in a week when both countries announced arrests related to alleged Chinese spying.

The recent arrests "shouldn't make us complacent, but rather spur us to catch those who spy against us and our security in our countries," Mr Scholz said.

The AfD in a statement on Wednesday said: "Any influence by foreign states through espionage, but also attempts to buy opinions and positions, must be investigated and firmly prevented."

It added that Mr Krah will not take part in the upcoming election campaign kick-off event.

Sky News contacted Mr Krah for further comment.