The communist intelligence service in Prague stepped up its spying campaign against Donald Trump in the late 1980s, targeting him to gain information about the “upper echelons of the US government”, archive files and testimony from former cold war spies reveal.

Czechoslovakia’s Státní bezpečnost (StB) carried out a long-term spying mission against Trump following his marriage in 1977 to his first wife, Ivana Zelníčková. The operation was run out of Zlín, the provincial town in south-west Czechoslovakia where Zelníčková was born and grew up.

Ivana’s father, Miloš Zelníček, gave regular information to the local StB office about his daughter’s visits from the US and on his celebrity son-in-law’s career in New York. Zelníček was classified as a “conspiratorial” informer. His relationship with the StB lasted until the end of the communist regime.

New archive records obtained by the Guardian and the Czech magazine Respekt show the StB’s growing interest in Trump after the 1988 US presidential election, won by George HW Bush. The StB’s first directorate responsible for foreign espionage sought to “deepen” its Trump-related activity.

A former StB official, Vlastimil Daněk – tracked down to the village of Zadní Arnoštov, where he lives in retirement – confirmed the Trump operation. Addressing the matter publicly for the first time, he said: “Trump was of course a very interesting person for us. He was a businessman, he had a lot of contacts, even in US politics.

“We were focusing on him, we knew he was influential. We had information that he wanted to be president in future.”

Facebook Twitter Pinterest The StB security file of Jaroslav Jansa, who reported on Trump in the 1980s while he was married to Ivana. Photograph: StB

Daněk said his senior colleagues at the StB’s headquarters in Prague were focused on Trump too. “It wasn’t only us who paid attention to him. The first department of the StB were interested in him. I don’t know if the first directorate shared information on Trump with the KGB. I can’t verify or deny.”

He added: “I don’t want to tell you any more details. It’s a past I would like to forget. I don’t want to have any problems.”

The files do not say if the Soviet Union ordered or shaped the decade-long StB Trump operation. But Czechoslovakian spies routinely shared secrets with KGB colleagues and the Moscow security agency had a large liaison office in Prague. Many StB officers also worked directly for the KGB, known as “the friends”.

In summer 1987, Donald and Ivana Trump visited Moscow and Leningrad, following a personal invitation from the Soviet ambassador in Washington, Yuri Dubinin. The trip was arranged by Intourist, a travel agency that was also an undercover KGB outfit. Soon after returning from Moscow, Trump announced he was thinking of running for president. That presidential bid failed to materialise.

In October 1988, on the eve of the US election, Ivana Trump visited her parents in Zlín, known at the time as Gottwaldov. According to the files she “confidently” predicted Bush’s victory to her father, who in turn passed the tip to local StB officers.

“The outcome of the election confirmed the veracity of this information,” StB field agent Lt Peter Surý wrote, in a document dated 23 January 1989 and marked “secret”.

The prediction came “from the highest echelons of power in the US”. Ivana was “not only a well-heeled US citizen” but moved in “very top political circles”, Surý stated.

Surý listed a number of “action points” that might be taken. They included remaining in “conspiratorial contact” with Zelníček. The StB goal was to gain more information about US foreign policy, politics and economy, plus “the activities of America’s intelligence agencies”.

Facebook Twitter Pinterest Marcela Strouhalova, a librarian, manages communist-era secret police files on Ivana Trump at the Security Service Archive in Prague, Czech Republic. Photograph: Petr David Josek/AP

Surý, who was deputy head of the local StB, still lives in Zlín. “Yes, I wrote that file,” he said, speaking about it publicly for the first time. “Trump was a rich businessman and interesting for us. I didn’t work on him, though. My colleagues did. The first department focused on him. I don’t know details.”

The comments by former StB officers suggest Moscow and Prague were intensely interested in Trump in the late cold war era. Spy agencies in both socialist capitals noted Trump’s growing political ambitions and sought to exploit his in-laws and family ties, using them as a dynamic intelligence channel.

'A very different world' - inside the Czech spying operation on Trump Read more

The scale of Soviet Moscow’s spying operation on Trump is unknown. No documents are public. It is unclear when the KGB began a file on the future president. In Prague about 60,000 StB documents were declassified in the mid-1990s, after the collapse of communism. The StB destroyed most records.

However, secret memos written by the KGB chief, Vladimir Kryuchkov, in the mid-1980s reveal that he berated his officers for their failure to cultivate top-level Americans. Kryuchkov circulated a confidential personality questionnaire to KGB heads of station abroad, setting out the qualities wanted from a potential asset.

According to instructions leaked to British intelligence by the KGB defector Oleg Gordievsky, they included corruption, vanity, narcissism, marital infidelity and poor analytical skills. The KGB should focus on personalities who were upwardly mobile in business and politics, especially Americans, the document said.