St. Petersburg, Russia - The two women thought to be Vladimir Putin's daughters made rare public appearances this week at a flagship economic forum in the Russian president's home city of Saint Petersburg.

Putin keeps details of his family life fiercely secret and has never publicly confirmed that the two women – Maria Vorontsova (39) and Katerina Tikhonova (37) – are his daughters.

But the pair have been widely linked to Putin through various media reports and in 2022, the US Treasury sanctioned both as "daughters of Russian President Putin."

On Thursday and Friday they appeared on panels at the Saint Petersburg International Economic Forum (SPIEF), Russia's flagship annual business summit where Putin will make a major speech later on Friday.

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Tikhonova, a technology executive who works in areas connected to the Russian military, spoke Thursday on a panel about the role of the defense sector in boosting Russia's "technological sovereignty."

"The sovereignty of the state is one of the key topics of recent years, it is the basis of Russia's security," Tikhonova said in her opening remarks, delivered via video link.

Vorontsova, a biology researcher who leads a state-backed genetics institute, spoke on a panel Friday about innovation in biodiversity.

Organisers listed her as a member of the board at the Russian Association for the Promotion of Science in the event's brochure.

Maria Vorontsova and Katerina Tikhonova have taken on more public roles in recent years, including some speaking roles at various forums and industry events. But public appearances are still rare.

Both have previously attended SPIEF as guests, but Russian independent media outlets reported it was the first time both have been part of the official program.

Putin has occasionally referenced the existence of "daughters" in public remarks during his quarter-century in power.

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Putin's now ex-wife, Lyudmila, gave birth to two children, named Maria and Katerina, in 1985 and 1986 while the two were married.

In the early 2000s, the Kremlin published a photo of Putin on holiday in which his wife and two blonde-haired teenage daughters were turned away from the camera, their faces obscured.