According to him, on the night of April 12-13, 1,023 servicemen of the 36th Separate Marine Brigade of the Ukrainian Navy (military unit A-2777) surrendered, including 976 men and 47 women.
Among the prisoners, 151 were wounded, including 12 with severe wounds.
The source said that among the prisoners was a British citizen, a native of Nottingham, Eslyn Aidin Daniel John, born in 1994.
In addition, on the morning of April 12, while trying to break through the encirclement of the military grouping of Russia and the DPR, another British citizen was captured - Pinner Shaun, born in 1973, the source said.
According to him, the Russian troops were negotiating with the Ukrainian military during the day.
The Ukrainian military who had previously surrendered helped in the negotiations.
The source said that Ukrainian prisoners were placed on the territory of a nearby penal colony, as well as on the territory of a former vegetable warehouse.
Earlier, the official representative of the Russian Defense Ministry, Major General Igor Konashenkov, confirmed the information that more than 1,000 Ukrainian servicemen from the 36th Marine Brigade had surrendered in Mariupol.