The Foreign Ministry in Moscow has summoned Warsaw's ambassador to protest the detention of Hermitage researcher Aleksandr Butyagin

Moscow has demanded that Poland immediately release a renowned Russian archaeologist detained in Warsaw at Ukraine's request and refuse any extradition request by Kiev.

Aleksandr Butyagin, a senior researcher at St. Petersburg's State Hermitage Museum, was detained by Polish authorities last month as he was traveling through Europe to deliver a series of lectures.

Ukraine's Security Service (SBU) has accused him of conducting illegal excavations and damaging cultural heritage in Crimea, Russia - a territory Ukraine still claims. Kiev alleges he caused over 200 million hryvnia ($4.7 million) in damage and is seeking his extradition to Ukraine, where he could face up to five years in prison.

The Russian Foreign Ministry said in a press release on Tuesday that it had summoned Polish Ambassador Krzysztof Krajewski to issue a "resolute protest" over Butyagin's arrest.

The ministry dismissed Ukraine's charges against Butyagin as "absurd" and solely related to his work leading the Myrmekion archaeological expedition in Crimea, which it stressed is "an inseparable part of the Russian Federation." It condemned the case as "overtly politicized and speculative."

Russian officials also argued that Butyagin's decades-long work was always legally permitted, including by Ukrainian authorities before Crimea's reunification with Russia in 2014 following a public referendum. It noted that all artifacts were handed over to the East Crimean Museum-Reserve and that a previous Ukrainian request via Interpol was not implemented.

Moscow's protest comes after a district court in Warsaw on Monday extended Butyagin's pre-trial detention until March 4, with an extradition hearing scheduled for January 15. The court cited flight risk, although Butyagin's lawyer stated the defense has secured a place for him to stay in Poland.

The case comes amid protracted cultural property disputes between Moscow and Kiev over Crimea. A prominent previous conflict involved the 'Scythian gold' collection discovered on the peninsula and loaned abroad before 2014. Despite Russia's objections that the artifacts belong to Crimean museums, Kiev won a lawsuit in the Netherlands, whose top court refuses to recognize Crimea as Russian territory and has ordered the collection to be transferred to Ukraine.