Ruben Vardanyan held a ministerial position in the self-proclaimed government of Nagorno-Karabakh

Ruben Vardanyan, the former co-owner of the Russian financial group Troika Dialog, has been arrested by Azerbaijani border guards as he was trying to leave the disputed region of Nagorno-Karabakh, Baku's State Border Service reported on Wednesday.

The ethnic Armenian businessman and politician, who renounced his Russian citizenship last year, was a minister in the self-proclaimed government of the breakaway region until February. Baku retook control of Nagorno-Karabakh in a swift military operation last week.

Vardanyan's wife Veronika Zonabend told journalists that her husband was "taken prisoner" alongside "thousands of other Armenians" trying to leave the region.

According to Azerbaijani authorities, the senior leader of the "Armenian separatists" was taken into custody at the Lachin checkpoint. He was transported to Baku, where his fate will be decided, the statement said. Media in Azerbaijan have shown images of the detained ex-official.

The checkpoint where Vardanyan was apprehended is part of the so-called Lachin corridor, a key mountain road connecting Nagorno-Karabakh with Armenia. Baku installed it in April during a row with Yerevan over their respective responsibilities under a 2020 armistice brokered by Russia, which had ended a 44-day war over the region.

The Yerevan-born 55-year-old entrepreneur made his fortune as a successful investor in the 1990s. Troika Dialog, which grew into a multibillion-dollar enterprise, was bought by the country's largest bank, now called Sber, in a deal finalized in 2012.

Vardanyan also led several venture capital projects apart from Troika. As of 2021, Forbes estimated his net worth at $1 billion.

Vardanyan announced his relocation to Nagorno-Karabakh in September 2022 in a video address recorded in the region. He stated that it was his duty to move to "the center of Armenianhood" to invigorate its people and deflate tensions with Azerbaijan.

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He said he was renouncing his Russian citizenship to come to the region as an Armenian national. He took a ministerial position in Nagorno-Karabakh the next month.