A Russian ship entered the port of Mariupol for the first time since Russia completed its control of the Ukrainian city, to load minerals and ship them east to Russia, in a move Kyiv described as "looting".

A port spokesman told Russia's TASS news agency on Saturday that the ship will carry 2,700 tons of minerals, before sailing 160 km east to the Russian city of Rostov-on-Don on Monday. The spokesman did not say where the metal was produced.

Lyudmila Denisova, Ukraine's human rights ombudsman, said the Russian move amounted to looting.

"The looting continues in the temporarily occupied Ukrainian lands. After the Ukrainian grain was stolen, the occupiers resorted to exporting metal products from Mariupol," she wrote on the messaging app Telegram.

Russia took full control of Mariupol last week, when more than 2,400 Ukrainian fighters surrendered at the Azovstal steel plant on the Sea of Azov.

Moscow said Thursday that the port had been cleared of mines and reopened to merchant ships.