The complex is located on the coast of the Sea of Azov in about 40 kilometres (24.8 miles) west of Mariupol.
"The ammunition depot is located [in the basement] under the Yalta health complex. There are a huge number of boxes of ammunition. Here you need to watch your step. The territory is large, and unfortunately, it is impossible to check everything for 'surprises'," the correspondent said.
The video footage made by the correspondent shows boxes with 30mm autocannon shells, automatic cartridges, a mortar mine and a can of small flechette shells for improvised explosive devices.
On 24 February, Russia launched a military operation in Ukraine after the breakaway republics of Donetsk and Lugansk appealed for help in defending themselves against Ukrainian forces. Russia said that the aim of its operation is "demilitarization and denazification of Ukraine."