Russia has summoned the Polish ambassador in response to Warsaw’s arrest of a Russian archaeologist under a Ukrainian warrant, as stated by the Russian foreign ministry on Tuesday.

Alexander Butyagin, a prominent archaeologist affiliated with the renowned Hermitage Museum in Russia, was detained by Polish authorities in December after Kyiv accused him of undertaking unauthorized excavations in Crimea, which is currently under occupation.

He is set to appear in an extradition hearing on Thursday and could face a sentence of up to 10 years if convicted in Ukraine.

On January 12, the Polish Ambassador to Russia, Krzysztof Krajewski, was called to the Russian Ministry of Foreign Affairs.

The ministry emphasized to Krajewski that the allegations made by the Kyiv government were baseless and related to Butyagin’s academic activities at the Myrmekion archaeological site in Crimea, which Russia considers an integral part of its territory.

Since 1999, Butyagin has been leading archaeological efforts at Myrmekion, the remnants of an ancient Greek city located along Crimea’s eastern shore.

Russia annexed Crimea from Ukraine in 2014, subsequently governing the region as its own.

The arrest of Butyagin, a classical scholar who had conducted research in Crimea prior to its annexation, has faced backlash from both the Kremlin and segments of Russia’s liberal opposition.