The BBC conducted a joint investigation into Russian documents together with the German magazine Der Spiegel, the German TV channel ZDF and the Italian newspaper La Repubblica.
The documents dating from 2017 indicate that close allies of Russian President Vladimir Putin believed that Frohnmaier, of Alternative for Germany (AfD), who was elected to the Bundestag Lower house in September that year, was very partial to their strategic interests.
Frohnmaier, who is based in the district of Böblingen, Baden-Württemberg, told the BBC he was not aware of the documents.
They were sent by email on April 3rd, 2017 to a high-ranking aide in Putin's administration calling for concrete “support” for Frohnmaier, 28.
The analysis describes Frohnmaier's chance of being elected as “high” and an assessment of his potential value to Moscow: “We will have our own absolutely controlled MP in the Bundestag.”
Another document obtained by the BBC, also from April 2017, appeared to be a request for help written on behalf of Frohnmaier's campaign.
“For the election campaign we urgently would need some support,” the letter stated.
“Besides material support, we would need media support as well… any type of interviews, reports and opportunities to appear in the Russian media is helpful for us.”
It pledged that Frohnmaier would focus in the campaign on topics including “Good relations with the Russian Federation: Sanctions, EU interference in Russian domestic politics.”
Frohnmaier 'not aware' of documents
The BBC said the document was part of a strategy paper outlining efforts to influence public opinion and officials across the EU on issues including Crimea, Ukraine and EU sanctions against Russia.
The documents were obtained by the Dossier Centre, which probes Russian attempts to gain influence abroad.
It is funded by Russian former oligarch Mikhail Khodorkovsky, an opponent of Putin who spent nearly a decade in jail in Russia.
Asked whether he could explain their conclusions, Frohnmaier said, in a statement from his lawyers: “Our client emphasizes that he was never under the control of any third party.
“Our client has not requested or received financial support… directly or through third parties.”
Frohnmaier has repeatedly called for an end to EU sanctions against Russia and visited Crimea, the Ukrainian territory annexed by Russia in 2014.
The AfD is the largest opposition party in the German parliament. It could not immediately be reached for comment.